A character who is effective because of their eccentricity.
Based on this Trope Repair Shop regarding Crazy Awesome.
Needs More Examples: the appropriate ones on Crazy Awesome need to be brought over (was planning to do this myself, but the homework is eating time. If someone else wants to, go right ahead.)
Needs a Better Description: More or less copied over from Crazy Awesome, with a little put in to make it seem more objective, still needs workInsanity Has Advantages is someone who's completely nuts, in an amusing way, and is effective at what (s)he does because of that craziness. In real life (s)he'd get fired from whatever job (s)he has/would have, or even arrested—at the very least, the things (s)he does just plain wouldn't work. But somehow, (s)he manages to be effective. What separates this character from being a plain old Cloud Cuckoolander, Bunny-Ears Lawyer and the like is that it is because of his/her extravagant madness that this character can function in the worst. For example: let's say The Chosen One's best friend, Ed Smith, wears a traffic cone on his head. Said traffic cone is spray painted metallic purple and has a grinning chimpanzee's face painted on the front. And Ed insists that you call it Sheldon. Yet despite this, Ed is very loyal to The Chosen One and can hold his own against the army of Mooks. So far, he seems like your average Bunny-Ears Lawyer, right? The traffic cone is an eccentric trait if there ever was one, but it's not necessarily why he's liked by the audience. Now suppose about ten episodes into the series, the Big Bad decides to drop a bomb on the Hero's city, and only Ed can do something to stop it. If Ed were to catch the bomb in his hand then kick it back to the Big Bad's jet, thus destroying them both, he's not this trope, he's a Badass Bunny-Ears Lawyer. If, instead, Ed pushes an inconspicuous button on the underside of Sheldon's base, and a jack-in-the-box chicken head springs out of the top and shoots Frickin' Laser Beams out of its eyes that disintegrate both the bomb and the jet in the space of five seconds, then for Ed Smith (and Sheldon), Insanity Has Advantages. In other words, it is because of Ed's quirkiness that he is an effective cast member. He would not be as effective (or, indeed, the same character) without the eccentricities. There can't be one without the other. Note that this is distinct from Power Born of Madness, although there is certainly overlap; a character can fall into this trope by simply being effective due to their quirks but lacking any derived supernatural powers, while a character with Power Born of Madness can be hindered by their insanity but compensate with their superhuman abilities.