I can only recall that happening to me maybe once or twice. I play SWTOR now, which is very similar to (as in copied a lot of design elements from) WoW (it feels like WoW in space), and I've never encountered all the NPCs being dead, even though the opposing faction is perfectly capable of raiding it.

You don't need to be flippant about it, if you are so worried about others "ruining" your gaming fun, when why TF are you playing an MMO? That's just like setting yourself up for disappointment.