If you consider only Fox News, then it becomes quite obvious that they always support the conservative, Republican viewpoint. I believe the other networks showed appropriate neutrality and respect for journalistic credibility during the debates, with even the Democratic analysts agreeing that Romney won the first debate.
People tend to be drawn to media that thinks the way they do. They will look for others who express their views, and that way reinforce their thinking. Now that we have 24 hour media, it is easier to find someone with whom you agree.
I don't think there's any way to answer for all people. I mean, if you watch a debate, you can decide for yourself who "won." You don't even have to look at/listen to all the media spin. So it really depends on who you are and how much you are willing to make up your own mind.