Here's the thing about the whole "Is FOX News biased" thing: There are two aspects of the bias.
The first one is choice of coverage. I once read a newsman state that all journalism is biased because you can only cover so much with limited resources (so many pages of newsprint, so many hours of broadcast time). A choice must be made what to cover based on the public interest and what the journalists themselves think is a worthy story. Obviously, by those two criteria, FOX News is doing no wrong when their morning show "FOX and Friends" mentions ACORN 23 times in a single broadcast but mentions a historic growth in the GDP twice. The journalists think it's right and the audience think it's right; Therefore, it is right ("Right" being the operative word here).
The other aspect is more clear (and more icky), and that is the expression of individual opinions on issues by the journalists themselves. To take the example of the aforementioned "FOX and Friends", this is the network's morning show, which means that it is supposed to be in the league of the Today show or Good Morning America. That is, it's a fairly pleasant mix of fluff and news stories by friendly people sitting on couches and comfy chairs. Well, ideally that's what "FOX and Friends" is supposed to be, but every time I have caught footage of that show and their hosts, I have always been repulsed by their transparent tone of smugness and acrimony.
Yet even having seen this in action doesn't prepare you for when they have a good laugh over someone yelling about Nancy Pelosi burning in Hell. I don't have a ready archive of broadcasts at hand, but I feel relatively safe is saying that nowhere in their history of any network morning show do you have Matt Lauer of Charles Gibson laughing about a politician's eternal torment. This is the key, FOX: Of all the programming on your channel, this is supposed to be the lighter stuff. You can go on and on about O'Reilly and Beck being opinion shows and not reflective of the network as a whole, but when you have stuff like this going on in your morning show, then it's not longer a debate about choice of coverage. It's about pure bile.