Humans, generally speaking, tend to give more credit to facts that already aligned with their pre-conceived beliefs than facts that are not.
This isn't exclusive to conservatives and liberals fall into this trap as well.
The problem is that Fox News and conservative media have figured out how to take advantage of it to further their agenda.
In fact, the RNC and Fox News has done an absolutely fantastic job of convincing their base that educated people shouldn't be trusted because they are liberal.