Maybe I is a dummy but, one of my ATF's was in a tuff spot and needed money.  I thought about it and decided she was enough of a friend that if I got screwed it was no big deal.  So I gave her money enough for a session.  My next visit she offered for free, but I figured money was still tight so I paid her.  I just didn't give her a tip until I had my money back.  Worked fine for us both.  Sometimes you just gotta trust yourself and other people.