When talking to people at work, I prefer to ask focus on policy. And tell them: Okay, disregarding his personality and focusing on his policy, what do you dislike about his policies?
Also asking them to clarify why they think a certain thing (eg. He is a racist) I ask them if they can provide me with examples. Trying not to attack them, but asking genuine questions helps to break their programming or at least plant a seed in their minds.
Had one co-worker who turned when I confronted him with the fact that he always ranted about how corrupt politicians were and that I found it odd when a complete outsider came in, he was not embracing that.