Left's sense of humor seems gone

Is it only me, or has the Left lost their sense of humor?

Outside of Jon Stewart, all other liberal-leaning "humorists" that I run across on the blogosphere or on TV just seem bitter rather than funny. (Stewart is simply brilliant.)

It is sad to see that someone like Garry Trudeau has turned from a major political humorist into just a shell of his former self.

(I usually don't watch SNL; the times I've caught Weekend Update in recent years it wasn't bad but I didn't detect much of an obvious ideological slant.)