Yeah, I think different men look for different appearances in women at different times. Some guys like tiny bodies, others like dramatic curves, others like a little fluff, others like a hard body athlete, etc. And because it's a relationship, the person and personality inside the body can become even more important (and sexier) than the appearance. And then there's just a quick fling, where maybe the standards are a little different from what a guy would want otherwise. Either way, most men aren't nearly as picky about female appearance as they seem to tell their wives or girlfriends. And that's fine - they're not animals who can't control themselves.
Most men universally do seem to find a relaxed, low key type who seems unlikely to flip emotionally to be appealing. I think that's a lot of Kate Upton ' s appeal. Although she has the same body type as Leticia Casta to me, and both got the same response from men even though LC is definitely not the American girl next door.
It's funny, the things that men will admit to a platonic friend vs what they've been trained to tell their gfs/wives. I brought up this Kate Upton debate to my bf and he automatically defaulted to "you're way hotter"... Like dude, relax. You're not in trouble, and we can have a conversation about another woman without me flipping out.
Most men aren't super picky but I have definitely seen enough of them sitting around the table with their guy friends dissecting a woman just like females do.