We used to mock wingnuts for Clinton Derangement Syndrome. Because they noticed that tag stung, they accused us of Bush Derangement Syndrome, even though CDS (Hillary murdered Vince Foster!) was mainstream in the GOP and BDS (Darth Cheney did controlled demolition of WTC4!) was only in the wacko fringe left.
The truth is that many wingnuts are simply deranged. They can't tell obvious bullshit from something that's in range of plausible. There are plenty of them, too, which is why our politics is so screwed up that a centrist like Barack Obama (bank rescue, Heritage Foundation health insurance reform, chained CPI, no accountability for financial crimes, gradualist war policy, weak on environment) has crazy teabaggers screaming "socialist commie fascist" at him.