It's true that all of us have a lifetime of work to do in that area, but I think the grandparent posted is referring to the people who cling to and consciously nurture biases.

Maybe my standards are too low but these days I'm excited to talk to anyone who even has a passing interest in truth for its own sake, no matter what the quality of their inquiry is.

If you love truth you will know those hidden corners exist and be alert to emerging evidence of biases and prejudices. There is the story which I suppose is true, of the professor who sat through a lecture and understood that the work being described had demolished the basis for his own work of the last twenty years. Rather than despairing he stood up and congratulated the speaker on discovering a better theory.