"Gwen is really on her game, and the collection is really rocking out the door," she said. "With Elizabeth & James, of course there is that cool factor of the Olsens being involved, but honestly, the collection is just fabulous, the design integrity is there and it fills a void on the floor."
Hearst said she just started selling the Conrad line, which is already performing well.
"Lauren Conrad sells to some who are fans of hers, but it's also attractive to those who don't know who she is," she said. "At a period where retail isn't doing so well, it's really nice to see these newer lines performing so well for us."
Erin Crandall, head buyer at contemporary online store Shopbop.com, said that she does quite well with many celebrity-backed lines, such as with Twenty8Twelve by S. Miller and Elizabeth & James.
"Brand name recognition is very important for us, especially since we are a Web site," Crandall explained. "A lot of times, it's good to be a celebrity brand since you see the name, and right away it will look familiar. For us, we've been selling L.A.M.B. for a long time and it has done very well. I think part of the reason is that Gwen wears it herself, whenever you see a picture of her, she's wearing something from L.A.M.B."
As for those celebrities who do not have lines yet, Crandall cited Lindsay Lohan and Mischa Barton as good possibilities.
"Lindsay and Mischa both have good style and I think a lot of people like how they dress, although I think Rachel Bilson has better style and I can see that line doing well," she said. "I'm also surprised that Madonna hasn't done a line. She seems like an obvious choice of celebrity to have her own line."
For DKNY Jeans, the partnership with Bilson gave the Liz Claiborne Inc.-owned brand a chance to address a more fashion-forward customer.