I agree with what Sigi said as well. I think these radio personalities, film makers, writers etc. are cheerleaders more than anything. They give folks what they want to hear and are certainly not converting anyone.
What I was referring to mainly were things such as M Moore and "Bowling for Columbine". Once it was discovered that much of his movie was simply not factual he decided it was satire, which made it OK.
Of course conservatives demonize liberals. It just seems like they are less likely to hide behind something to do it. Anne Coulter sure doesn't. Even she spooks me at times