Intimidating your Players (or at least their Characters)

So I'm gearing up for another session of Firefly tomorrow and was reading the rules regarding PC vs. NPC interaction when the rules showed as an example an NPC trying to intimidate a PC.  In the example the attempt failed, because the example was meant to illustrate how a player could jack their die roll total up, but it left me wondering what would have happened in the game if the NPC had successfully intimidated the PC.

Players often intimidate NPC's.  For that matter they also frequently bluff, trick, seduce, haggle, or otherwise bamboozle NPC's in a generally social/intellectual manner.  Sometimes this is done strictly through roleplaying but over the last, oh, fifteen years or so it has been resolved through skills.  Roll high enough and they will believe that the sound was a reactor malfunction but that everything is under control and how are you.

What I don't see a lot of is the flow going in the other direction.  In fact I can't think of the last time I had an NPC attempt to pull a fast one over on a PC and resolve it through a die roll.  I've had players roll "insight" or "detect motive" or some such thing to try to ascertain if their GM is lying his ass off to them, but generally an NPC has to rely on my own roleplaying chops and not on random chance.

I'm trying to imagine a scene where I, as the GM, tell someone "Baron von Shnorkel glowers at you imperiously and demands you tell him the truth. (die roll) He succeeds and you tell him everything you know."  I can imagine the howling that would occur.

"Kneel before Zod!"  "Sigh, okay."
(Is that Bill Cosby in the background?  Now that's damned awkward.)

This is actually a tension I feel about RPG's in general. I get why we stat out physical abilities, because that's how we resolve combat and similar challenges.  I even get intellectual skills, since I can barely jump my car's battery, much less fix an engine.  But social attributes I've always found a little hinky, because at that point you've take a lot of roleplaying out and swapped in a die roll.  I get nonathletic people playing strapping heroes, or liberal arts majors playing starship engineers, but socially inept people playing suave con artists starts to make me wonder why we play the game.

I've gone a little far afield here.  Do you allow NPC's to dictate social or emotional responses in PC's based on die rolls?  Can a group of PC's be conned simply by luck?  How do you, if you're the GM, work that out in your own game?