In the real world, on the other hand, you usually have tons more information about a potential partner. This complicates matters considerably. On the one hand, it makes it more difficult to concoct a fantasy sexual scenario with that person as your ego-ideal (which is what, I think, a lot of men like porn for--beautiful women without the complications, who don't say I'm too tired tonight, who never make you feel insecure, etc.) On the other, it gives you a lot more to work with psychologically. And I know that for me, this is where it gets interesting. If a person can turn me on intellectually, they can probably turn me on physically. I'm not someone who is obsessed with a certain "type"--male/female, tall/short, blonde/brunette, whatever.
Perhaps this pieces me into the "men just like big titties" generalization, but I am the opposite from you. If I am too much the same as a romantic interest, I like them too much as a "friend". The more we can relate, the more detached I find myself romantically. I have a very specific aesthetic quality that moves me to action, and it isn't as specific or dull as hair colour or eye colour or whatever, but it is definitely there and specific nonetheless. For this reason, none of my friends are girls, only the ones I've dated, or the ones that are dating my friends.
I'm not sure if this is a masculine thing, but from what I can tell about myself and other guys I know, we tend to be a hell of a lot more objective.