"Honest" is a good way of putting it. They have a bias -- that is, a set of values through which they interpret the facts. But they don't ignore facts, or just make them up, in order to justify their bias.

They understand that the world is complicated, and that multiple world-views have to coexist despite disagreements on what facts mean. They make arguments based on their own world-view, but they'll be sound arguments on that basis. They reject bad arguments, even those whose conclusions nominally agree with them.