I would say that I enjoy the sex at least to some degree most of the time. I enjoy it a lot maybe 25% of the time. Sometimes, I find it unpleasant, although it's rare that it's actually awful.
I admit to being shallow enough that if they are very ugly, I am turned off. I once had a hideously ugly man give me oral with the best technique I'd ever experienced and I faked an orgasm before I could suffer the indignity of him getting me off. (He was both hideous and annoying as a person.)
I saw someone fairly recently whom I suspect is on the Autism spectrum and found him very odd, awkward, and stiff - it was unpleasant to be touching him naked and even talking to him was difficult, although he wasn't a bad guy.
I know a lot of girls say that they like the older gents but once they're about 70 or older I find them very unattractive and they always seem to have this weird, palsied way of clutching at my flesh - sporadically and desperately grabbing my boobs, running their liver-spotted hands over my body - that makes me cringe internally.
I sometimes really enjoy myself - it helps if they're attractive in some way, but obviously a lot of it is technique and chemistry. That said, what I really enjoy in my extracurricular sex life is feeling free to let go and be selfish or not having to feel in control. My favourite lover at the moment is someone who chokes me and slaps me (gently, I must say) and I really get off on letting him do whatever he wants. I could never let myself go that way with a client.