Exactly why do you think he's a douche? You know him personally?
And also, even if he's a douche how does that stand in the way for you to like his music? Have you actually listened to any of his bands?
Not trying to assault you or anything, but I just don't see any reason in hating one of the best musicians ever because you think "he's a douche".
I watched Faith No More live last summer and some of my friends, whom never had listened to any Patton projects, were immediately converted by his genius. Really, see him live. It'll most definitely change your perspective of him.
I've tried listening to all of his music and I fucking hate it all. But there's no doubt he's talented, wouldn't put him in the genius catagory tho...
Seriously why and how is Mike Patton a genius.
Because he can basically tackle every genre of music and make something great out of it.
He is one of the most versatile vocalists alive and can do about anything with his voice; singing, crooning, falsetto, opera (listen to the end of Faith No More's Land of Sunshine), screaming, death growl, rap, beatboxing, etc. You name it.
And on top of that founded and runs Ipecac Records which, IMO, is one of the most interesting record labels (together with Hydrahead) today, spawning bands like; Bohren and Der Club of Gore, Isis, Melvins, Zu, The Locust, Desert Sessions, etc.
So yeah, he's without a doubt a musical genius.