The statement doesn't have to be true. If a jury finds that the defendant reasonably believed the statement to be true, then the defendant will win. Take a look at the transcript of WWASPS v. PURE, which is probably linked on here somewhere, but I found it on ISAC. It's several hundred pages, but you can just look at the jury's verdict toward the end. The standard of proof was higher in this case because WWASPS was in the category of "public figure." To find PURE, et al. liable, the jury would have had to find she made false statements with actual malice.
Does anyone remember the Jerry Falwell v. Hustler case? Fun stuff. They printed a Campari ad where they had been having different celebrities talk about their first time drinking Campari. The ads sort of had a sexual connotation about the "first time." Anyway, they had Falwell talking about how his first time was in an outhouse with his mother. It was friggin' hilarious. He sued over it and lost, because it was so obviously a joke. It doesn't really relate much to any case against ISAC or anything, but I thought it was funny. I guess the point is that when you have a public role, you have to put up with more shit than the rest of us. And no one on the jury felt sorry for the WWASPs people who make a bazillion dollars a year.