It cuts both ways. We don't trust the media, and we don't trust the politicians. So when a politician says that the media is lying, we tend to believe whatever we want to believe.

The loss of truth is a serious thing for a society. (Yes, back in the Walter Cronkite days we had less truth than we thought we did. We had more agreed-upon truth that matched reality than we do today, though, and I think the difference matters.)