When we judge someone to be inferior or wrong, or even right then we stop listening to them. If we think that they are inferior then why should we listen? Our ideas are clearly better. If we think they are wrong, then again why waste our time listening? If we judge them as silly people then everything they say will seem silly. If we deem them to be usually right, then you don't have to listen, they are right so let's just move on.
Don't judge at all. Listen to the speaker each time as if you don't know them. Once they are finished, you can express opinions and pass judgements on what they have said, but don't apply those judgements to the next thing that they say.