Well, as a guy massaging a nude woman I always prefer to wear shorts or something. Does the woman getting the massage really need to see me massaging her with a good hard on? No.... It happens from time to time. Why would I want that? I do not...so, I wear some shorts usually.
I have always left it up to the client's preference, draping is always offered. Most prefer to be nude during their session. If they ask I always let them know I am also a fellow nudist. I have been fortunate to have a varied clientele, including men and women from the ages 8 to 80.
I have a lady i massage, and every time she wears underwear. First time she has a towel cover also.
Then next time she made sure the room was warm/ hot enough and just said its OK, don't replace the towel. I would try to work around the underwear, but in the end she agreed to let me pull down. Then the following time she didn't bother with towels at all, told me OK to take underwear down. Funny when she then said don't bother putting back on. But every time now she still wears underwear, but when i get to her bum she gets me to remove her underwear for her haha