Used to quite enjoy dealing with the completely unreasonable passenger you can find on any flight (after the cabin crew had tried their best).
I found that if the captain was seen to be dealing with the perceived grievance as politely and reasonably as possible the rest of the pax would gang up on the complainer.
Best example was the chap sitting three rows behind the offender who stood up and said, "Captain, why don't you just tell him to f**k off?"
Saved me the trouble.