Actually, there are cis men with cellulite, too. It's a combination of fat distribution and the way the skin elasticity deals with it, and while it's *more* common in women, there are men who fit those parameters as well.
I'm not sure why this argument is about passability? Obviously, if there's a hypothetical trans woman who's ONLY female feature is cellulite, she's not going to pass. But, Teresita, you seem to be the only person even talking about passability to begin with. Everyone else is just sharing their feelings about cellulite itself. (Oh, and only now do I notice this thread's from 2010...)
And for the record, no, I don't think cellulite is what makes people read me as a cis woman; I think it's a side effect of the fat redistribution and accumulation HRT gave me. To be honest, I wish I knew what *did* make me "pass" 100%, because I live in constant fear that it'll change and I won't know how to fix something I never understood in the first place...