My point? It's all about execution, what you do with "worn out" encounters. In this instance, killing rats in the basement is no mean feat (there are lots, and they swarm if you're not careful) and turns into an amusing and dangerous quest with a moral quandary, lore about lycanthropes and more than one solution.
Completely agree. I actually have something planned where the player is asked to investigate the basement of an inn and it's strongly hinted that rats are the problem...but it turns out to be something far worse (and the "quest-giver" was perfectly aware of that fact from the get-go).