99% of the time when men get rejected is because their standards are just too high.
I also think that of lot of guys have been brainwashed by the movies, where the dork always somehow gets the hot girl.
Another mistake that many men make is that they go for girls who are too young (by too young I mean girls aged between 14 to 20+).
But most of the time teeny boppers are just not mature enough to be able to reciprocate a older man's feelings.