I like the "tip more and smile" suggestion. We did that at a restaurant where our server was being run ragged by a party of four who were acting as though they were eating their last meal. They complained - loudly - about the food, service, table location, etc. Meals were sent back and had to be replaced. As a result, we got less attention from our server. She apologized, but probably didn't expect much of a tip. (And she certainly wasn't getting one from the whiners.) We left an extremely large tip and, yes, we felt great about it! Probably will be labeled as stupid by the terminally negative, but it sure made us happy.