(Parent post is mine as well, wasn't logged in earlier.)
Yes, I have watched MSNBC, and no, I managed to miss the incident you're describing on CNN. This largely misses the point -- the fact that it's POSSIBLE to miss whatever "Bush=Hitler" incident you saw on CNN, while I can turn on Fox or spin the AM dial pretty much at random and land in a positive feedback loop of "liberals are destroying America."
I don't watch much Olbermann, but I have seen conservative guests on Rachel Maddow's show (plus a lot of "so-and-so declined our request for an interview"). You can object to her tone during her solo segments if you want, but I have yet to hear her be less than respectful to a conservative guest, even if she's doing her damnedest to dismantle his or her argument at the time (note: calling out bullshit is not the same thing as disrespect). Compare this with the O'Reilly "cut his mic!" shoutdowns over at Fox.