Unlike some folks (no need to point fingers, ya know who you are) I started out life dirt poor and put in my fair share of time in the customer service industry. So I usually tip quite well because I know these people who are busting their butts to prepare and serve me food live off tips. I just use a simple scale to tip.
Rude/terribad = no tip
average = 15-20%
good = 30%
Everything but a happy ending = 50%
Life rule number 1!!!! NEVER screw with people who prepare your food or handle your money. If you think you can get away with being an eletist jerk who is "above the help" I assure you that more than one meal of yours has been prepared with just a little "extra"....FYI "Please" and "thank you" go a LONG way in preventing this, don't be a jerk.
hahah ok after workin in the food industry a while myself hahaha...i have never EVER spit in someones food..no matter how rude they were to me...don't get me wrong ive thought of all the things i could do..but i have never spit or anything in someones food...