Most people spout “Judge not, lest ye be judged” because they do not want what they are doing to come under condemnation!
Had a teachable moment with my son the other day. A TV character said "Don't judge me" and I asked the boy, "What does somebody really mean when they say 'Don't judge me?'" It didn't take him long to figure out the lesson: "Don't judge me" is code for "I know what I'm doing is wrong, but I don't want to hear about it." I went on to point out that if someone believes what they're doing is right, they don't ask you to withhold judgment; instead they defend what they're doing.