It seems we've been into talking about our favorite characters and most hated characters lately. In keeping with the zeitgeist, then, what are your favorite/least favorite plot devices, especially the ones that seem generally disliked/liked?
For me, I've always had a soft spot for "hero stumbles into amazing experience/manual and becomes amazing." Yes, it looks like they're way too lucky and don't have to do any work, but luck comes to the prepared, right?
On the other hand, I've always disliked the plot device of "being stupid" (e.g. Romeo not getting the letter from Juliet and deciding that means he should chug rat-poison). In the world of wuxia, the example that comes to mind would be Ah Zhu's death. That was stupid.
EDIT: These plot devices can come from the novels or the adaptations--want to include everybody here, including those who haven't read the novels or translations