I'm at the more "mature" end of the spectrum shall we say. However, thinking about this question, the youngest girls I've seen, say under 25, have on average given a far better service than ones that are older.
Once they get into the older bracket, i.e. over 40 then they tend to get good again.
When I first started, I was concerned at what young SP's would think of me, now I don't care, as has been said, I'm paying for a service and I find the bigger the age gap, the bigger the turn on. But then I'm just a dirty old perv