in the broadest terms:
Men are hot.
Women are interesting.
Pre-pubescent boys are adorable.
Pre-pubescent girls are cloying.
Teenagers are gross.
Obviously not all men are hot, (ie. men I find sexually desirable) and not all women are interesting, (worthy of friendship and conversation) and my observations of the pre-pubescent are confined to memories of my own youth and brief encounters with children of friends and acquaintances but I think that sums it up in a nutshell.
Oh, and ALL teenagers are gross to one degree or another, even the "nice" ones. That transitionary period between youth and adult is repulsive on so many levels.
OT: why the fuck doesn't Spellcheck recognize the word "transitionary"?