I don't understand why people tip. I never tip. Sometimes tips are included in cheque as a flat percentage, that's fine for me as long as it's stated before order. But why would I pay more than necessary to someone who did his work? That makes no sense for me. If you're not paid well, leave and find another work, that's none of my business. I'm not that rich to throw money around to everyone who wants it.

And if the service is bad, I'll require to fix it or decline to pay at all.

I guess that cultural thing.