One time a friend and I were having dinner out at a nice restaurant. At the table next to us was what I'll call the Obnoxious Family. Mom, Dad, two small kids. The kids were running around and yelling. Throwing food on the floor, spilling on the tablecloth, rubbing crumbs into their hair. The waitress had to bring refills for their drinks twice, because the kids kept spilling them.
The parents were worse. They complained about every single item that was brought to their table. The rolls weren't warm enough. Not that the rolls were cold, mind you. Just that they weren't warm *enough*. There was too much ice in their sodas. They asked for extra croutons on the salad and not tomatoes, but didn't get enough croutons. Everything they ordered had some change from the menu, either an addition or subtraction or substitution. They claimed that none of their special requests was correct. (Which I found odd, as this restaurant was very good at special requests and a lot of people with allergies eat there because they are so good with the special requests.)
How did we know all this? Because they kept broadcasting their displeasure in loud tones that echoed throughout the dining room.
Their waitress was almost in tears at one point--I thought the dad was going to throw a plate of food at her. She was running back and forth, really trying to get things right for them. She brought the manager to them at one point and the manager tried to both assure them that the restaurant was doing its best to cater to them, and also to get them to rein in the kids a bit, which they finally did. The manager also comped their desserts because they complained so much.
When they finally left, they announced loudly to the waitress that they were not leaving a tip, because her service had been so poor. All of us at the surrounding tables were not pleased.
When the waitress came back to the table to start to clean up the mess--with the overturned glasses of soda, the crumbs on the floor and the chairs--she was a little surprised to find out that she did have a tip. Everyone at the surrounding tables had been sliding a dollar or two under one of the plates--I think she ended up with about $25. Not really enough to compensate for dealing with that family, though.