DangerousPuhson
My my my, we just loooove to hear ourselves don't we?
I am firmly anti-quirk, and instead prefer to focus on the motive, means, and opportunities that NPCs have, since I think it pushes one to focus on what is relevant to their presence in the game.
I think we need to define something before I can respond in earnest: what do you consider a successfully-run NPC to look like? How do you know you have built a successful encounter with an NPC, and most importantly, by what measures are we to ascribe "success"? I think our answers may differ.