I think you're suffering from a bit of david broderism. "I want to look reasonable, so I'll say both sides do it".

Fox News viewers are the least informed viewers in every survey ever conducted. They thought that Saddam had been caught with WMDs in like 2007. Almost a majority thinks Obama wasn't born in America. These are scientific surveys, and it's completely different from a liberal being biased to explain away facts that they acknowledge.

If Fox News is saying something, and people are repeating it, I think we're doing them a disservice by saying they don't really believe it.