Last night, MSNBC's Rachel Maddow sat down with David Letterman on the Late Show to talk about conservative media outlets. After Maddow cited her usual hangups about Fox News and Andrew Breitbart, Letterman aired his own feelings. "I have a theory about Bill O'Reilly -- smart guy and I think he knows better than what he's doing. But he's just found a place to make a living. He would be a weatherman if the money was right."

Letterman, who has famously sparred with O'Reilly on his show, continued. "He's just doing this because that's where the money is. I don't think you can be as smart as he is and actually believe what he [says he] believes."