So when I observe someone saying "that guy is racist, don't believe his arguments", I can recognize that this is an emotional claim. It's an attempt to demonize a person rather than refute the argument. I can then observe that no one is disputing the actual argument, evaluate that on merit, and have a true belief about the world unbiased by my desire not to affiliate with racists. I can also update my beliefs about the rationality/honesty of the person saying "hey that guy is racist".
Conversely, I can also recognize that a desire not to be racist is strong in people, and exploit it when I want to manipulate the less rational. For example, if I'm arguing against economic protectionism with an emotionally driven person, I might use Jim Crow as an example of protectionism rather than occupational licensing.