Most places won't even accept it. They'll think it is some sort of class gesture, like you are giving them charity / handouts.
Vietnam it is part legal (it is a socialist country) but in Japan, people do their job because it is their job, not because they can get a tip. It's a different type of societal mentality.
I once had a group of cute Aussies come in order 4 big steak dinners with a bunch of beers. Got great service as they were cute and I liked talking to them hearing there accents. The wankers left me nothing. I thought it might be a cultural thing as I know british don't tip either. A lot of euro's like FOB don't tip cause it is not part of there culture. They pay wait staff and bar staff hire there and tipping is not needed.