All based on the service and how I feel.

If a waiter is always refilling, checking on the table, and enjoying his job, I tip the Bullshit standard of 15% plus because this is America, lol.

If the waiter is "just" doing his job, I will leave him under 15%. Why? I feel that if he is not enjoying his job, my shitty tipping will drive him to find a job/career that he likes. Yes I said it, and I mean it.