Yep, RR, that bit I understand. But surely in principle you wouldn't charge them for a truly bad meal regardless? I know it's a question of how significant the complaint was...
There are only two ways to live your life. One is as though nothing is a miracle. The other is as though everything is a miracle. - Albert Einstein
If I was on the premises I was in the kitchen and no one ever had an "atrocious" meal. If the meal passed through my hands I knew it was fine. The complaints were always minor and I offered this deal to even those about whom I had serious doubts.
And there were many nights where I oversaw, garnished and touched every plate when we served 500 meals.