It's not all guys. [EDIT:] I would say it's more likely that 1) they aren't ready to commit, or 2) they're still undecided. Some men don't ever know what they want.
My guy hardly notices people. I'll say something like, "Damn, she was hot!" and he's looking around like, "Who?" (Of course, it could just be that my idea of hot and his are not in sync) I look more than he does; but not to everything that walks or breathes. Very specific/picky about what I think is hot.
JR, You're a GUY!?!?!?! Whoa, learn something new every day!