The most-recent issue of Imprimis has a good account by Fred Barnes of mainstream media bias. Link. Excerpts:
President Bush is similarly treated as someone who is obsessive about his religion. And what does he do? Well, he reads a devotional every day; he tries to get through the Bible, I think, once a year; and he prays. Now, I know many, many people who do this. Tens of millions of people do it. And yet the media treats Bush as some religious nut and pursues this story inaccurately. Again, it is clear that partisan bias is involved, too, because in fact, Bush talks publicly about his faith much less than other presidents have. There is a good book about Bush's religion by Paul Kengor, who went back to every word President Clinton spoke and found out that Clinton quoted scripture and mentioned God and Jesus Christ more than President Bush has. You would never get that from the mainstream media.
I read The Media Elite when it came out in the mid-1980s. It did an excellent job of setting forth simple facts (e.g., 90% of journalists at the big newspapers and reporters at the networks vote Democrat), but also of describing more nuanced things, like the way conservatives are referred to as "conservatives," but liberals are never referred to as "liberals," and how conservatives are often shot in unflattering ways by the camera (e.g., facial close-ups).
Like Barnes, I thought the bias declined for awhile in the late 1980s and 1990s. I guessed that maybe the MSM itself was a little embarrassed that its own preferences had become so obvious. But also like Barnes, I noticed that the bias has seemed to be getting worse the past couple of years, especially when dealing with issues of religion.