I recall many years ago, as a college student, meeting up with a provider overseas.  We had already done the deed, and as we were lying together in bed, she began to tell me some sad story in her life.  I couldn't help it, but I started crying, pretty uncontrollably.  I don't remember if I felt so bad because of her problems, or because I was feeling so ashamed of myself for "using" someone who had such a rough life.  

I saw her again at a 'normal' bar a couple of nights later, and she wanted to hook up again.  I told her I didn't have any money, but she said it was gratis this time.  So she took me to some dingy motel, and we had not-so-great sex again (my fault, I have no control).