Major designers selling chic fashions at mass market. Sports leagues outfitted by fashion's top names. Celeb-designed lines now cover everything from slogan tees to entire collections. But is any of this really design, or is it very clever merchandising?

"If a tie-in brings people into the store, or makes them more aware of a brand name, then perhaps the next time they're shopping, they'll remember that brand. It's good for awareness and merchandising, even if it's not always the highest form of design." - Tom Kolovos, stylist

Retailers work with celebrity tie-ins for differentiation and exclusivity, says Anne Brouwer, senior partner at retail consulting firm McMillanDoolittle, Chicago.

"These partnerships are for retailers looking to set themselves apart, and bring an edge to their offerings," Brouwer explains.

Younger consumers are more prone to be influenced by such collaborations. Men and women ages 13-to-34 are significantly more likely than older consumers to say they get their clothing ideas from fashion magazines, TV shows and celebrities, according to the Cotton Incorporated Lifestyle Monitor™ survey.

Monitor data reveal that celebrities influenced the wardrobes of 12% of women and 6% of men. Among women under 35, however, the percentage jumps to 24% of those aged 13-to-24 and 18% for those aged 25-to-34. Among males, the percentage jumped to 12% among 13-to-24, and 9% for those 25-to-34, according to the Monitor survey.

Ultimately, though, celebrities-turned-designers must have good product to have any staying power. Tom Kolovos, Chicago-based stylist and contributing fashion writer to NBCchicago.com, says some celebrity-designed lines are better positioned for success than others, citing the new Material Girl by Madonna collection, a collaboration with Iconix Brand Group that is exclusive to Macy's.

"Madonna had that knack for being two beats ahead," Kolovos says. "That's what fashion editors try to do, too, so that consumers think they have their finger on the pulse. So Madonna has more credibility than other celebs because she's consistently a step ahead of everyone, and therefore able to give a new perspective. Her line could be interesting."

While Madonna's new line might have staying power, McMillanDoolittle's Brouwer says that's not always the case; "The risk is whether there's a long enough life cycle to make the investment worth it," she notes.

Some people might dismiss celebrity lines as all flash, no original fashion, which might be the case with cast members of MTV's hit show "Jersey Shore."

Jenni "JWoww" Farley recently launched Filthy Couture, a collection of mini dresses and bikinis. Cast mate Mike "The Situation" Sorrentino teamed with Miami-based Dilligaf by Bohica Bill™ to launch a line of "high-quality wearable art" that will be called Dilligaf Couture by The Sitch.

The collections may not be high fashion, but the "Jersey Shore" pair cannot be blamed for wanting to strike while the iron is hot.

Andy Sernovitz, who wrote Word of Mouth Marketing, told Women's Wear Daily recently, "Fashion is word-of-mouth. When you bring a celebrity into fashion, what they do bring is a pre-existing fan base." Sernovitz points to Facebook and Twitter as evidence that celebrity links today are more powerful than ever. A celebrity with a million Facebook friends could recommend a certain jacket and it is as if a friend is suggesting it – only the item receives instant mass exposure.

Of course, if the celebrity gets into hot water, brands may want to dissolve their association. Take for example, Tiger Woods' negative press of late.

"That's the problem with a celebrity being attached to something – you don't have control," Brouwer says. "There is risk that they could shorten the lifecycle or damage the brand."

Aligning a collection with a TV show or movie is another potentially lucrative angle, since Monitor data reveal that 19% of females and 13% of males look to television as a source of clothing ideas. The younger they are, the more likely they are to turn to TV for inspiration: 25% of 13-to-24 year olds, versus 8% of those aged 56-to-70.

"If a tie-in brings people into the store, or makes them more aware of a brand name, then perhaps the next time they're shopping, they'll remember that brand," Kolovos says. "It's good for awareness and merchandising, even if it's not always the highest form of design."

Some designers, hoping to connect with men, do so through professional sports. John Varvatos dressed players for the 2010 NHL Awards. JA Apparel's Joseph Abboud brand clothed NFL coaches and now is the official designer apparel partner with the New York Giants. And DKNY became the first fashion brand to secure a permanent presence in Yankee Stadium through a long-term, multifaceted sponsorship deal.

Though consumers may be swayed by celebrities on or off the field, they still look for what is practical in new apparel: price (85%), fit (83%), color (64%) and style (55%) are deemed most important. Style and brand name are significantly more important to the younger 13-to-34 set, (62% and 25%, respectively) than among those 35-to-70 (47% and 15%).

Ultimately, says Kolovos, consumers may be most driven by that pragmatism. "In this economy, designer originals are priced too high for most people," Kolovos says. "But if a lower priced collection is selling at Target, or if a line is linked to a movie, the inspiration for it is irrelevant to consumers. If it works, it works."