I hate to tell you, but all shows with a live audience do that. I was in the audience for Funniest Home Videos once (hey, somebody has to do it!) and the floor manager (I think that's what he was called) bascially said that we had to laugh as hard as we could at anything we found remotely funny. And of course, because people have made the effort to show up and be in the audience, they don't want to just sit there, so they laugh at the stupid fucking jokes. But Rove is just a stupid unfunny little shithead.
And I don't like Letterman either. I dunno, he just seems too smug for a mostly unfunny old guy. The gimick segments are kinda funny (Top 10, Is This Anything? for about two runs through, Will it float? ditto), but then, that's what they're made for - to distract attention away from the unfunny host.
Why has Rove got the gold Logie twice now? And why the fuck is he so arrogant that he was to be drawn holding the Logie in the 10 ad?