Why don't members of serious news shows call out Rush, Hannity, Beck et al.?

The things these people say are so absurd and so regularly dishonest that they should not be given a free p in my opinion. So why do real news outlets just gloss over the insanity they spout? It's almost as if they don't actually listen to these shows to see what these guys actually say. I see the Sunday morning talk shows full of people who seem terrified to call a spade a spade. Perhaps because of ratings? Perhaps because they enjoy the political benefits of the influence they exert? Is it because they are afraid of being called "liberally biased" by calling water wet?