I watch Leno. Then I watch Conan. I laugh my butt off. Then I turn off the TV.
There is nothing incredibly interesting or funny about the man. I'm sure he's a nice guy, but he's never said anything funny while I was watching him. Or did I miss a funny episode... oh, wait, no, there was never a funny episode.
I have, unfortunately, at least once, stared at the TV with my jaw on the floor (likely the same expression on the faces of his audience) trying to figure out whether the last statement he made was a joke. If it was, it sucked. He just blabs on and on, making no sense.
Oh, and these bands he brings in all sound the same and no one's ever heard of them before. Oh, yeah, and they suck.
I'm pretty sure they figure, "well, he's in a bad slot, so his... two... viewers... are pretty good!"