Confirmation bias exists. When you look for it, you start seeing it in various forms every day, some of which are violent and extremist.
When you form a habit of noticing this pattern, you also know which opinions to dismiss, because you know they were formed through the skewed lens of confirmation bias.
My hypothesis is that it is possible to take this too far, to a point where you disregard any and all opinions of someone you have classified as a biased person. You may lose out on valuable insights based on who said it rather than what they said.
Not even <insert controversial personality here> is wrong 100% of the time.
And there is a term for the situation where you believe something so strongly that you are blinded to the exceptions and nuances that defy your beliefs. That term is confirmation bias.