gives an example of how a misinformation meme can develop and propagate to political ends. Trying to determine which side of the political spectrum is more willing to rely on misleading rhetoric seems kind of silly. However it might be interesting to find some structural forces at work.
On the right, talk radio and direct mail have been major actors. On the left, I think you really saw this in the netroots internet phenomenon reacting to Bush. In both cases, there was a technological process for delivering this sort of "red meat" to a political base, which becomes self-sustaining. You see this obviously with FOX, and MSNBC trying to do the same on the left.
Then there is the more tricky business of looking at other, more subtle structures. Demographics might be interesting to explore. Then there's the philosophy itself - what it means to be a conservative or liberal, and how each might lead one into a willingness to buy into misleading rhetoric.
There seems to be a strong element of personality type that will take a hard - and sloppy - stance no matter what political movement they find themselves in. Altemeyer and others look at this when they argue for an Authoritarian model of the psyche. Yet separating out personality from political movement is difficult.
I think though the strongest factor at work might be either side's feeling of struggle, whether revanchist or simple political determination. Fundamentalist Christians have always couched things in apocalyptic terms. Marxist revolutionaries have their classless, multicultural, etc. utopia. Philosophy, whether religious or political, has a very specific role to play and is dependent upon historical variables. For instance, gay rights is a major motivator for Christian fundamentalists, yet changing social mores have lessened their sense of urgency. The fall of communism dealt a major blow to Marxist thought, at least for those who would view communism as a viable Marxist enterprise. Groups are highly affected by current politics. In the 90's there was mass rebellion against Clinton, in the 00's it was Bush.
In the end conservatism seems much more confident in its view of itself as a sort of current utopia. If the liberals just went away the perfect order we've achieved would be fully realized. Thus state of perpetual defensiveness and revanchism seems to exist. The only thing standing in the way of maximum liberty is big government. Such a broad claim invites broad rhetoric, opening the door to error.
Progressives have their own peeves with conservatism, but are less defined by it. Whereas in the past progressives were defined by a dogmatic opposition to business, most have now come to view it as something to embrace, albeit with caution. There is a structural point of philosophical nuance here that hinders hyperbole, a sure sign of misinformation.