I had a group of players in a Curse of Strahd campaign. They started killing soldiers in Vallaki indiscriminately and leaving behind their bodies - not even looting them! So I had Strahd return a bag of things they “left behind” including a letter from a loving wife about how much she missed soldier A, a drawing from a child for their father soldier B, a locket with a picture of soldier C and wife, etc.

They didn’t like that.