In many Asian restaurants both inside and outside Asia, and also on some Asian airlines such as Korean and JAL if I recall correctly, hot cloth towels are given out to all passengers before each meal.
I know they're for cleaning your hands prior to eating but I've never been sure whether it's correct etiquette in the relevant Asian cultures to also use the towel on my face. I'm always too shy to ask.
I've definitely seen other westerners use them on their face and I've done so myself and found it very refreshing, but I've always been a bit worried that I might be doing something other people might find vulgar or even disgusting since I know ideas of hygiene vary widely and in surprising ways around the world.
(I'm not asking if I should do it, I'm just asking if it's good or bad etiquette in Asian cultures. Obviously it's my choice whether to regard other passengers'/diners' sensibilities or not.)