Kristin Cavallari (L) and Lauren Conrad attend MTV's "The Hills Live: A Hollywood Ending" Finale event held at The Roosevelt Hotel on July 13, 2010 in Hollywood, California. Credit: John Shearer/Getty Images for

Seeing is believing, as the stars of MTV's The Hills know all to well.

During an appearance on Bravo's Watch What Happens Live Dec. 3, former bad girl Kristin Cavallari admitted the reality show was "pretty fake." During her two seasons on the show -- she joined the cast after Lauren Conrad departed midway through season 5 -- Cavallari said she had a series of "fake relationships" and "fake fights."

"But it was fun," the star admitted, "because [when] you're acting, it was more fun for me."

When host Andy Cohen asked which cast member she regretted dating the most, Cavallari said "no one" -- not even Justin "Bobby" Brescia, who also dated costar Audrina Patridge for several seasons.

"I would say Justin, but I never really dated him," Cavallari, 25, said. "I think I made out with him once and that took a lot of convincing. Finally I was like, 'All right, I'll just do it!'"

When Conrad, 26, appeared on the Oct. 16 episode of Watch What Happens Live, she was asked to say three nice things about her Laguna Beach and Hills nemesis. Cohen, 44, asked Cavallari to do the same Dec. 3.

"She is a very pretty girl -- I know she said the same thing. She's very successful," Jay Cutler's fiancee said. "And we actually have had a lot of really fun nights together, so she can be a lot of fun."

Cohen then asked Cavallari if her "distaste" for the fashion designer was scripted, to which she laughed loudly and shouted, "No!"

Cavallari, who welcomed son Camden Aug. 25, then clarified, "I feel like [producers] put things in our heads. I mean, we were 17 and 18. They made it a lot worse than it was."