Some sites don't do this. When it became clear that the 2003 invasion of Iraq was misguided, the propaganda sites did not jump on board. When Rumsfeld finally admitted we weren't going to find weapons of mass destruction the right-biased sites changed the narrative and started trying to make other stories dominate the news cycle.

It happens on the left as well (watch some of the MSNBC shows). That's the difference. It shows up in the willingness to criticize your own team.

My wife is a news junkie. She actually watches CSPAN along with all of the news channels. Sometimes I catch the same story from a few different places, and it is clear they ALL apply their own bias. For a current example, Fox tries to pluck out emails from the leak that show some wrong doing and MSNBC has a story about a leaked email sharing a risotto secret.