In our second adventure, Adrienne, playing the rather flightly male Eladrin warlock Tralamin, made a series of really bad perception and insight roles. And so it came to be that Tralamin determined that, since they all felt a great tranquility washing over them, they must be in the burial chamber of the Gnollish Queen of War, and not Peace-- and, in a keen bit of role-playing, wondered why the other chamber was filled with such hostility; that the ancient, magical door that appeared to be completely identical to the one they found in the Firepalm mine was "clearly" unrelated; that the group of Fire Dwarfs which attacked them upon exiting the Sacred Tomb of Gnollish Kings had no interest in said door.
In each case, Stephanie, playing the elven bard Robyn, also rolled the same check, came up with a better result, and then quietly shook her head to the other players, mouthing the word "no", rolling her eyes. Which seemed of apiece to her similar reactions regarding Jarmingle's less-than-impressive swashbuckling.
I talked to Adrienne a few days after the game, and asked her how she felt about that botched rolls. She really enjoyed them-- enjoyed that the character was so completely convinced that he was right, even when he was very very wrong, and enjoyed the way it fit into her Eladrin-as-Ann-Arbor-hippie characterization. Thusly encouraged, I asked her if we could make this a regular bit of shtick for her character-- every time Tralamin would need a perception or insight check, I'll assign an abnormally high difficulty class. Rolling a natural 20 would still allow him an occasional glimpse of being right, but in most cases, he would say the most ridiculous, off-base nonsense possible-- kinda like Wolverine's heightened senses, but in reverse.
This would also allow other characters-- such as Robyn-- to quietly make their own checks and to politely let the other players know that, no, those trusty Eladrin senses are wrong as usual.