It is just in some people's nature to complain a lot. Sad, but true.

The toilet overflowing sewage onto their carpet is definitely a legitimate complaint. If it took a steward three hours to respond to a call to get the husband off the deck, that is a legitimate complaint, but we really need more facts on that one.

If the rest of the stuff was about mundane stuff like lines, food, weather, so what? Most people take that kind of stuff with a grain of salt.

I still don't see any evidence of a scam. It actually sounded like they were happy with the 20% discount and the $500, which sounds like fairly reasonable compensation for the toilet issue.