I think there were a lot of people who didn't get the irony of "America, Fuck Yeah!" Parker and Stone don't always directly poke fun at something. They will present whatever they are making fun of in such an over-the-top manner that you SHOULD be able to discern that they're satirizing it. Like the Passion of the Jew episode. They don't believe that Passion of the Christ will turn people into Nazis. They're making fun of the people who think that the film will stir anti-Semitic feelings.