Bias has nothing to do with the black kettle idiom I'm afraid.

Let's all of us please drop with the accusations. Really. No more of the "You're this"s and the "You're that"s, or the "You don't know what you're talking about"s.

It's becoming an overused expression on this forum and is, besides, very assinine in nature - if someone's wrong, don't tell them, show them.