I vote for the dislike of loud moaning or "oh god's" I keep thinking it's fake for my entertainment. Purring, however, is more positive, especially if nicely massaging an escort or stripper. The more subtle body signs mentioned like quivering etc. On the other hand, from doing lots of relaxing massage, certain body movements can also mean you are falling asleep.
It reminds me of decades ago in Victoria, BC, I had an escort on top of me that did fall asleep. Ah... gentle movement by me, but trapped under her body... How do I wake her up?