If you are a people-pleaser (and this doesn't necessarily carry a negative connotation), then it's a good tactic for any employer to play the victim card by talking crap about previous "walkers" in order to instill loyalty. You don't want to be a "walker", do you? ;)

Actually, I think you should pay extra precaution when dealing with "trashtalking victims", because I think the risk of dealing with a toxic customer is greater than losing a bit of revenue from someone who was genuinely burned.