Never does a man portray his own character more vividly than in his manner of portraying another.

Your account of another person is largely an account of you. The qualities you notice first, the motive you assume, the detail you find worth repeating: all of it comes out of your own furniture rather than theirs. That is why an unkind account of a third party makes the listener wary of the speaker, often without them being able to say why.

Listen to yourself the next time you sum somebody up in a sentence. Ask whether you would be content for them to hear it, and whether the version you gave was the most accurate one available or just the most convenient.