Many restaurants have the audacity to add a 20% (or whatever percentage) "service fee" that isn't considered tip. It even says something like "we use this to pay our staff competitive wages and health insurance." You can't opt out. It's just part of the bill. Then they have the gall to ask for a tip on top of that.

I've taken to a) leaving a negative Google or yelp review for such establishments and b) never coming back. This is a practice that needs to die.