How do you deal with this mismatch, either as a game master or a player? Do you play it as-played, so that the only character who can seduce the scheming noble's wife is the only player who can pick somebody up at the bar? Or do you play it as-written, so that the character can bluff the guards into letting him pass, even if the player's best effort is "I've got an urgent message for, uh, Lord Blah-blah-blah"?
I want the player to make the effort. We've all stretched ourselves, at one point or another (I hope!), to play beyond our comfort zone. Not necessarily a whole character, but maybe a scene or scenario that we aren't necessarily good at doing ourselves, but we want our character to be. Otherwise we're just playing ourselves each time we roleplay.
All that said, I do want the player to make the effort. I want them to try That's all I ask, really - that an attempt be made. If they're not living up to what's on their character sheet, I'll have them roll and adjust the NPC's reaction(s) accordingly.
If it's not a diced game, then things get trickier. But again, everyone gets more than points for the effort. They have to tell me what they're trying, how they're trying it, rather than, "I seduce Barbara," or "I bluff the guards." Give me something to go on, and I'll let a LOT slide. Something like, "I (or my character) will flatter Barbara, buy her drinks, get her to talk about herself. Definitely get her to tell me everything about herself. I'm going to wait until I think the time is right before I suggest that we go back to my place - so she feels she can leave any time she is uncomfortable." Or "I fast-talk the guards. I wave some papers in front of them, shouting about how Lord Folderol needs these urgently, since I've been sent from his country estate. He's now a grandfather, and he has to know about it NOW, because it's not the grandson he was hoping for...basically spin a tale, but talk fast so they can't understand it and probably won't remember it. And I'll spit as I talk, so they'll want to wave me on quicker."
Those sorts of examples will make me smile as a GM, or as a player. We have one player in a game I'm in, and all he wants to do is play the stats and skills. He tells the GM just about every session that he's trying to intimidate someone (usually into attacking him), and then he rolls the dice. Never once does he say what he's trying to do, how he's trying to do it, what he's saying, etc. Pisses me off that the GM lets him get away with it. I'd love to just hear a little something, even once. How about a "Your mother wears army boots!" or "What kind of pansy-assed fighter do you think you are?" But it's not my game, and it's not how that player wants to play. Which is why I'll never invite him to be in any game I run.