The Old Couple [spoilers]

SPOILERS.

The old rude couple that went over the top about their reservations at the beginning and at the end of the movie were living in their own brainwashed fantasy bubble. After all the crap that Lisa went through and dealt with it's understandable that she told the couple to "shove the comment card up their behinds", it wasn't right, but it's understandable, there's awful things going on in the world and they want to complain about a wrong reservation, they got refunded and the hotel receptionist was not even rude to them, so there was no problem. That couple are the type of people that love to complain because they dislike people in general, there's too many people like that in this world unfortunately.

Lisa could have taken the high road and just walked away or she could have just told them politely to not return if they hated it there that much.