Why is it my responsibility to do performance reviews of restaurant employees? The management already forced me into a performance rating system through tips, I shouldn't have to sit down with the manager to do a detailed performance review too. Besides, if the food and service was so bad that it warranted a $0 tip, I'm probably not coming back.
For one thing they have no idea if you have a legitimate complaint, are someone who has such high standards that it's not worth catering to, or simply a cheap bastard. They care strongly about the former, will shake their head at the middle and will dislike you if it were the latter.
If you actually speak up they'll have a better idea.
My point was that if the service was bad enough to not leave a tip, complaining to the manager might result in you not paying for the food, either.
You can demand that the bill be discounted or waived entirely (or that what you paid be refunded) if you didn't get what you were expecting. For instance, if you walk out of a movie because the sound was a half second out of sync and the picture was out of focus, you could just eat the price of the ticket, or you could find a manager and get your money back for the low, low cost of just voicing what was wrong with your experience.
What else would you do? Angrily write a bad Yelp review in your car?
I don't care about getting comp'ed food (unless the order was obviously wrong and I was over charged), that's not going to make up for the 2 hours of wasted time. I'm not going to spend another 15 minutes waiting to talk to a manager while I "demand" that the bill be discounted or waived.
Fortunately, I live in an area where there is no end of new restaurants to explore, if I have bad service at one, then I just won't go back there. Problem solved (for me).
For the record, I've never tipped 0% (but have tipped only 10% for particularly bad service).
