If you're actually asking the question, I'll give you my answer: I was lucky enough to go to a nice spa resort earlier this year, I just handed a few bills to an attendant who had laid out a towel for me when an older man sitting next to me chuckled and shook his head saying "You don't actually have to give them them anything, they have to do it anyway." Super nice resort, nobody here hurting for a few dollars in tips.

I guess it's valid to take everything you legally can, but personally, I'm saying it's fucked up move not to pay even a token amount. That's their only consequence, (some) people thinking it's a fucked up move.