Recently at Pharyngula, Myers started discussing the difference between conservative and liberal characters. There's one point I want to expand on here - humour.
There are two major areas of humour I'd like to consider - not the only two, but they cut a large swathe through the field of laughs. The first is subversion or category displacement. The joke teller sets up an expectation and then subverts it. They lead the audience into making unexpected mental connections. The second is that of cruelty, of inviting the audience to engage in shared derision of a target. You'll note this doesn't cover the entire spectrum - "The Aristocrats", for example, falls into neither category.
So let me suggest a crude spectrum which correlates with libralism/conservatism - that of neophilia vs neophobia. Neophilia is a liking for the new - people who enjoy learning, who enjoy ambiguity and incorporating new concepts. Neophobia is a dislike of the new - people who are made uneasy by the ambigious and resist concepts which clash with those already held.
Neophiliacs gain considerable enjoyment out of the first kind of humour mentioned above. They enjoy having their expectations subverted, being led into a constant stream of category misfirings. Neophobics do not. It makes them uneasy. They don't enjoy playing with expectations. At worst, they are unable to follow the huimour because they are unable to process new concepts fast enough. There's something happening, but they can't figure it out.
Both ends of the spectrum, however, can enjoy cruelty.
Now, consider Mallard Fillmore, that most conservative of comic strips. Its sole payoff is group identification through stereotypes and derision of "The Other". Solely. It doesn't do irony or humour as liberals understand it.
Consider Chris Muir's Day by Day. It tries, but it so often fails to get that category misfiring. But, boy, does it press the shared derision button. And the tits-and-ass factor, of course.
Consider relatively apolitical comic strips which, on my observation, have a huge following amoung liberals. Opus, for example. Or consider the politically liberal cartoons, such as Doonesbury. Or consider the Colbert Report, Jon Stewart, Bill Hicks, the whole swathe of liberal comedians. They get the vast majority of their laughs out of category misfirings - that's what satire is, and irony too, to a lesser extent.
Now, consider a recent thread at Pandagon on the vocabulary of the White House. I'm quite proud of one of those entries - "Isolating extremists", which a commentator named Cris described as "humor that hurts". That makes it a success. That's what it was supposed to do - express a sense of righteous fury by presenting an image that triggered horror and pity at the exact same time it was funny through category misfiring. The backstory is, of course, that that little Iraqi girl screaming on a concrete floor is an orphan - she's covered in the blood of her parents shot in front of her at an American checkpoint. She's about as isolated as I've ever seen another human being. You get that. I get that.
I suspect the wingnut end of the conservative grouping simply wouldn't get that. They don't play around with subverting categories - to them, I would just be poking fun at the kid. They might consider it a bit tasteless, they might consider it disgusting, but they wouldn't consider it funny.
Especially not funny in a way which allows us to demonstrate our fury at such situations.