I took your question as sarcasm, If it wasnt I apologise.
If it was sarcasm then you answered your own question.
Do I get a lot of practice at defending myself from being called cheap? I do not.
I also get good service when I return to restaurants where waiters do a good job, because they receive a good tip.
I agree with you that the amount of a tip should be proportional to the quality of the service. Personally, extremely poor service gets 10% from me, rounded down to the nearest buck, and maybe a word to the manager. Otherwise it's 15%-25%, sometimes rounded up to the nearest fin.
Oh, I have my answer alright.