If the character Bruno were a straight dude, and pulled the same stunts I've seen in the trailers, he'd get the same reaction from people. They seem to be reacting to his absurd behavior, not his sexual orientation.
Well, it mostly goes beyond that, and it is about sexual orientation.MAJOR SPOILERSOne of the most famous "incidents" in the movie is where they staged a WWF Wrestling showdown called "Sraight Dave's Man on Man Smackdown" or something like that in Arkansas. The advertisied it around town as a $5 admission, $1 beer, and the promises of scantily clad women. What it then turns into on purpose is sudden gay sex with the host Bruno dressed as "Straight Dave" and his "lover" in the ring, and it's quite explicit. Kissing, licking eachothers nipples, going for a blow job, etc. The crowd becomes absolutely unglued and furious. Violence breaks out. It's amazing they weren't killed.
There are also lots of other over the top gay sex scenes depicted, that are meant to be quite in your face. Lots of dildo action, leather play, and even a champaign bottle up the butt.
However, it's quite funny when they're handcuffed together in leather gear and they go running after the Westboro Baptist Church members, and they are freaking out trying to run from them.