I think a drape is required for spas - although I have had some fun in them. I have also tried to be undraped to be covered up / some guys start using over the sheet first -- So there have been a few guys who keep it on but more often than not when I say I am fine without the sheet if you are, they usually are, and if he isnt you have you answer.
I book sure things mostly but it is hot (i find anyway) if there is a will something happen. But move it along unless you are cool with just te massage and blue balls lol. And always jack off before the massage so u dont go as quick if you get hard! I have a therapist tell me that LOL