If I paid for a massage with HJ, I should not assume I can touch her. But if I had paid for a B2B then I dont think some touching (within limits) is too much to expect?
I think if you pay for a nude hj, it is acceptable to touch, just don't be too rough or try to touch pussy. I'd in doubt you can always ask, and they will tell you. If you ask nicely usually not an issue.