First, the AMP girls you think are under 30 are more often than not over 30.
Secondly, while a few guys (mostly newbs) like to qualify their reviews with how young they are, how fit they are, or how big their dick is, the VAST majority of AMP girls are more concerned about two things: how kind you are (how you treat them) and how wealthy you are (how often can you see them). I say this as an overweight guy under 40 with a fairly high disposable income that consistently treats the girls with as much respect as I can, and my YMMV is consistently on the high end.