I think a more important question is: how young of a girl would date you.
I'm 31 going on 32, and just returned to school after being laid off. I'm taking pre-reqs at a community college right now, so I'm surrounded all day by teenage girls. I'm sure that more than a few are probably freaked out by my attempts to make conversation, etc. (ie- what's this dirty old man doing trying to talk to me.) ha!ha!