They have seemed pretty unbiased to me. About the only thing close to it, I would say is perhaps when there is something where there is no evidence for one way or another, they may give an opinion. But whether the myth/legend, etc. is declared as fact or myth seems to be looking at just the evidence. And if there isn't enough proof, it should rightfully be declared a myth, or listed as 'uncertain/unknown'.
Please list some examples of what you feel is biased, false, or your thoughts on their grading system (should probably start a new thread, so we aren't hijacking this thread too much).