For average service, I tip 12 percent on the bill total. To offset the tax added.
If someone is shit, I give 'em a good three or four percent, plus a written note on the receipt to get fucked. Usually accompanied with a frowning face.
Like another says, they're taking my order, bringing me a plate and checking in on me at some point to see if I'm OK. Maybe top up my root beer. All with a smile.
Big deal.
I'll be equally pleasant and toss ya 12 percent. Now move along.
Fortress has shit to do.