No matinee idols for Louis Vuitton. Its latest poster boy, Keith Richards, has deep wrinkles, smudged eyeliner and unruly hair as he sits strumming a guitar in an untidy hotel suite. And Antoine Arnault, Vuitton's head of communications, couldn't be more pleased. "We thought it was important to continue with someone unexpected," Arnault said of the Richards ad, slated to break in a range of general-interest titles in April. "I think when people are flipping through a magazine, this will stop them."

A legendary guitar player and a founding member of The Rolling Stones, Richards is the latest personality to appear in Vuitton's "core values" campaign, designed to underscore the brand's travel heritage and classic monogram leather goods as a balance to its fashion-driven marketing. Launched last fall, the first batch of ads -- starring Mikhail Gorbachev, Catherine Deneuve and tennis deities Andre Agassi and Steffi Graf — will continue to appear in tandem with the Richards image. The new spot comes with the tag line, "Some journeys cannot be put into words," and the rocker's haunting, hypnotic expression says it all.

Arnault recalled that, when Annie Leibovitz displayed the photograph on a computer monitor after the shoot, Richards exclaimed: "It looks like a Rembrandt." Albeit one with many rock 'n' roll details, including black scarves printed with skulls covering the table lamps — a Richards touch — and a custom-made Vuitton guitar case tossed on the bed.

A team of designers at Saks Fifth Avenue envisioned "a piece of modern art" and hired a renowned graphic artist to create it. Their counterparts at Lord & Taylor demanded five prototypes, even traveling to a Korean factory to oversee manufacturing. Over at Bergdorf Goodman, staff members held secretive deliberations that stretched late into the night for nine months. The focus of all this scurrying was not this fall's couture line or next spring's resort collection. It was shopping bags.

Once a flimsy afterthought in American retailing - used to lug a purchase home from the store, then tossed into the trash - the lowly, free store bag is undergoing a luxurious makeover. From upscale emporiums to midprice chains, retailers are engaged in a heated competition to make the most durable, fashionable shopping bags. They are investing millions of dollars in new flourishes like plastic-coated paper (Macy's and Juicy Couture) and heavy fabric cord handles (Abercrombie & Fitch and Scoop).

Behind the battle of the bags is a significant shift in behavior that has turned consumers into walking billboards for stores. In cities like New York, Chicago and Los Angeles, customers have begun treating shopping bags as disposable purses that can be reused for weeks, if not months, to carry laundry to the cleaners, books to the beach or lunch to the office. But only the best bags make the cut. So stores, sensing a marketing opportunity, are racing to transform bare-bones bags into lavish, thick ones that will become free advertising. "It's an unspoken goal," said Terron E. Schaefer, senior vice president for marketing at Saks, which just redesigned its bags to be sleeker and heftier. "We want people to keep the bag."

It was almost a brilliant idea. Trendy handbag designer Hogan just launched a groovy range named after rock chicks. They called a pony-skin version the Chrissie, after Chrissie Hynde - who is a prominent anti-leather campaigner. Oops.

"I never thought I'd be moved to consider filing a lawsuit, but as soon as I heard my name was being used to promote bags made of dead-animal skin, I started exploring my legal options with my friends at PETA," Hynde told Gatecrasher. "At first, I thought this must be a joke, it's so outrageous and thoughtless." In the past, Hynde's passionate aversion to leather has put her on the other side of the law.

In 2000, the Pretenders front woman was arrested after trashing the window display in the Gap's flagship Times Square store. She and fellow PETA protesters destroyed leather pants and jackets that featured in Gap's heavily publicized "Everybody in Leather" campaign. A spokeswoman for Hogan did not return calls yesterday.

The Shrek star visited the historical Machu Picchu site with a green bag which had a red star and the words "serve the people" printed in Chinese. It evoked memories of a Peruvian war against Maoist rebels in the 1980s and '90s, when up to 69,000 people died. Diaz admitted she did not realise the slogan's "potentially hurtful nature". "I sincerely apologise to anyone I may have inadvertently offended," she said in a statement released to the Associated Press.

"The bag was a purchase I made as a tourist in China." She went on: "I'm sorry for any people's pain and suffering, and it was certainly never my intention to reopen what I now know is a painful wound in this country's history." Diaz wore the bag while sightseeing at the Incan city of Machu Picchu And she spoke of Peruvians' beauty and warmth, saying she wished "for their continued healing".

Her appearance with the bag had drawn criticism from prominent local human rights activist Pablo Rojas. "It alludes to a concept that did so much damage to Peru, that brought about so many victims," he said on Friday. "I don't think she should have used that bag where the followers of that ideology did so much damage."

Women rarely go anywhere without a purse, which means that if a woman enters a place full of germs, so does her bag. That could mean she ends up carrying around microbes that could make her sick all day long. Microbiologist Chuck Gerba researches where organisms that make us sick lurk and lately he says he has found that germs gather on the outside of a woman's purse, especially on the bottom. "We found fecal bacteria you normally find on the floor of restroom," he said. "We found bacteria that can cause skin infections on the bottom of purses. What's more amazing is the large numbers we find on the bottom of purses, which indicates that they can be picking up a lot of other germs like cold viruses or viruses that cause diarrhea."

Using a hand-held germ meter, Gerba demonstrated how much bacteria can grow on a woman's purse for ABC News, with results that ranged from scary to downright terrifying. Health experts worry when the meter reads over 200, which means thousands of bacteria are present. He found thousands of germs on one woman's purse. She bought her bag about a month ago and Gerba's measurements showed her purse also carried thousands of germs. ABC News is not naming the women who participated in order to protect their identities. "I'll probably just get a new one," she said.

Yet another woman has been carrying a handbag around for years and Gerba said that he found "hundreds of thousands of germs on the surface." Gerba found about half a million bacteria on the bottom of one woman's large bag. Each time ABC News and Gerba ran an instant field test and later a lab test on swabs from the outside bottom of 10 women's purses, every single one had at least some bacteria, most had tens of thousands and a few were saturated with millions. One even had 6.7 million bacteria. Half of the bags tested positive for coliform bacteria, which indicated the possible presence of human or animal waste.

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"It matters because you can move germs that can cause illness from one location to another," he said. "You can later touch that purse and get them on your hands, or you could put your purse near a food preparation area and transfer germs to areas you may touch during food preparation." Some women argued that they do not lick the bottom of their purses, so they should not be in danger of getting sick, but it is very easy to unknowingly transfer germs. For example, whatever touched the bottom of your purse touches you when you grab it. If you eat a sandwich soon after that, the germs go right into your mouth. "The purses are really becoming subways for micro organisms," Gerba said. "They're being transferred from one location to another. So it's just like germ 'public transportation.' I'm afraid to touch them. You know, I know too much. I'll never become a purse snatcher, believe me."

The hard-partying pop tart asked for a purse at the Heatherette show Tuesday, but a fashion source tells us that heiress-model Lydia Hearst turned her down - and it may be because she thinks Spears isn't a good role model. The singer had wanted to be presented with the pocketbook backstage and promised to carry it to her front-row seat at Heatherette, where she would be photographed with the coveted clutch, the source claims.

But after Hearst - who had only 100 of the PUMA bags she designed with Heatherette's Richie Rich and Traver Rains - politely declined her "offer," Spears was a no-show. Leslie Sloane Zelnick, the singer's spokeswoman, told us: "It's not true."

Hearst told us: "I'm only giving the bag to accomplished young women who are doing something positive to affect the world around them. They are women I look up to and respect, like Gwyneth Paltrow and Sarah Jessica Parker and Anne Hathaway. They share the same high standards of giving back to the communities in which they live."

Women cite a variety of reasons. Some, like Ms. Azizian, hope to head off an argument with a penny-pinching husband or boyfriend. Others feel guilty spending lavishly on themselves, and so they prefer to pay with cash, which is more easily forgotten than a monthly reckoning. A handful say they simply feel a sense of freedom from pulling the wool over their husbands' eyes.

While hard data is difficult to come by, the number of women paying in cash for designer goods has increased in the last several years, according to retail analysts and interviews with 10 upscale boutique owners nationwide and employees for chains like Neiman Marcus and Nordstrom. "Women buying luxury goods in cash is a fast-growing phenomenon," said Marshal Cohen, an analyst for NPD Group, a market research firm that conducts 45,000 online interviews about consumer habits each week. Mr. Cohen, who interviews as many as 100 shoppers weekly, said women reported paying with cash to disguise purchases as low as $150 and as much as $10,000. "Their answer to why they're doing this is always the same," he said. "Their husbands or boyfriends don't identify with the need to own such pricey items, and cash shopping affords them independence."

Howard Davidowitz, who has studied consumer habits firsthand for decades, said that in the last three years he has seen more cash purchases at luxury boutiques like Louis Vuitton and semiluxury chains like Coach. Mr. Davidowitz, chairman of Davidowitz & Associates, a retail consulting firm, suspects now that $2,000 handbags and $700 shoes are commonplace, more women pay in fresh bills from the A.T.M. to cover their tracks.

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"Women have this fear about their spouse's reaction to their shopping bills," said Amy DiFrisco, who was a witness to cash buying as a personal shopper at Bergdorf Goodman for nearly a decade. "Cash lets them avoid that confrontation." As the owner of a clothing boutique, Two Blondes, on the Upper East Side, she continues to see the cash habit. "It was surprising at first, but now it's no big deal," she said.

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Men certainly aren't above treating themselves. But the difference, psychologists say, is that men are more likely to be open about buying an iPod or a $2,500 case of 2003 Château Pavie for their wine cellar, even if it leads to an argument. "In my experience, when men make money, they assume it is theirs," Dr. Potash said. "Women, even if they earn their own money, sometimes feel compelled to ask permission to buy things."

In the last few years, bags have become ever more voluminous, and as women have fallen sway to their chunky charms, they have filled them up with necessities. These days many women are as burdened as mail carriers. As a result, reports of shoulder soreness and stiff necks are on the rise and doctors, massage therapists and chiropractors are tailoring treatments for the bag-obsessed.

"In the last year or so, I've been seeing the same kinds of issues with adult women that I'm used to seeing with kids who carry heavy backpacks on one shoulder," said Karen Erickson, a chiropractor who has a private practice on the Upper West Side, and also serves as a spokeswoman for the American Chiropractic Association. "They’re experiencing neck pain — not just while they're carrying their purses, but all the time. A lot of women even get bad headaches." "Lately, when a patient comes in complaining of these symptoms, I walk over and pick up her purse," she added. "Without fail, it weighs a ton."

For the past several months, Robin Ehrlich, the director of the Eastside Massage Therapy Center on the Upper East Side, has observed clients old and new staggering under the weight of huge purses and griping about neck pain. "It's an epidemic," Ms. Ehrlich said. "We're busier than ever before right now and big bags are the reason." A common side effect is that one shoulder becomes slightly higher than the other, she said. "A lot of women talk on their cellphones while they’re carrying these bags, which only intensifies the problem, because in addition to balancing too much weight on one side, they’re lifting the shoulder at the same time."

Ms. Ehrlich recommends weekly massages for the pain. Gentle stretching and warm baths with Epsom salts can help bag abusers, too, she said. But she would never tell a client to ditch her Mulberry Elgin tote. "It's like telling a woman, 'You cannot wear Manolo Blahniks,'" she said. "It's just not realistic."

Kors' 25-year-old company is counting on his unprecedented visibility to kick-start its ambitious plans for expansion. The question is whether Kors' vision can keep pace with his celebrity. Kors faces challenges that eager Runway contestants can only imagine. To take on profitable giants like Ralph Lauren, Kors must devise a look that seems essential and current. Today, Kors makes uncomplicated, classy sportswear—the industry term for coordinating blazers, pants, shirts, skirts, and knits—and to succeed financially and creatively, he must find an inventive way to make these classics new, as other great American designers have.

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In the absence of much choice, Kors' many die-hard customers—well-heeled women who work and well-heeled women who don't, but want to convey the efficient independence of those who do—rely on his easy way with chic. But in order to expand the business, the company must attract a larger pool of clients. In 2003, industry veterans Silas Chou and Lawrence Stroll bought a controlling interest in the Michael Kors brand, and in August they announced plans to open 100 stores worldwide. The company is banking on a cross-merchandising strategy aimed at drawing big spenders and budget-conscious shoppers into the same stores. Each will sell clothes at several price points: The Collection—or runway—label will hang alongside two accessibly priced "diffusion" labels: Kors Michael Kors at the "bridge" price and Michael Michael Kors at the lower tier. The plan also calls for expansion of the men's offerings and the potentially lucrative accessory collections.

The partners clearly mean business: Company President John Idol spoke of the brand's $1 billion potential. But it's not clear that Kors' newfound TV stardom will make this effort more successful than earlier, failed strategies.

Note the gaudy colors. The diagonal zipperish scars. The carroty tufts and deceptive "playful" quality. Do not leave this purse alone with your son! Unless you're tired of raising him and would find his death convenient.

The ancient amphibian-freak from 1954's Creature From the Black Lagoon boasts "centuries of passion pent up in his savage heart." Though equally repellent to the touch, this Isabelle Fiore bag ($650) has little to recommend it beyond a "zip-top" and two unsavory pom-poms. Furthermore, the Creature only lashes out in self-defense while the Charm Hobo spent months in a dark basement plotting—actually, the less said about the Charm Hobo the better. We don't want to encourage any more copycat school shootings.