Do mundane spell-less Disguise roll effects have any duration? For instance, say you make an extraordinarily good Disguise roll that stumps every NPC's Perception. Can you just maintain that Disguise indefinitely for the rest of the game, or would you have to reapply your makeup (aka roll Disguise again) after a certain amount of time?
Realistically I would assume that you'd have to roll again once a day at least to represent you putting back on or adjusting your fatsuit, mask, makeup or whatever, but the rules seem to say nothing about that.
EDIT: I believe I accidentally put this in the wrong forum. My apologies if that is the case.
I would play it as you suggest. You might have problems with a mundane disguise if you have to literally sleep with the enemy.
For a long term disguise, you could make periodic rolls but not let any single roll fail. Just as some poisons require two saves in a row, you can make it so that someone only sees through the disguise if they make multiple checks.
I'm with Watery Soup, here.
The Disguise skill will almost always require Bluff along side it, yeah? So maybe in a long-term situation, a low roll with either gives you a penalty to the other. Something like that.
As for a specific duration, I'm a huge fan of White Wolf Games's most common duration: a scene.
Talking your way past a guard to get info the fancy party? Less than a minute in game time, also one scene.
Mingling with the noble muckity-mucks at said fancy party? A few hours, but still one scene. At least, until the mysterious figure beckons you into the other room to deliver an ominous message. Now that's a new scene. And going back to the party, armed with new information, that's another scene.