Not only do people rarely want to admit a flaw about themselves, they are always quick to explain to others that they shouldn't "judge" them. People act like it's the worst thing in the world for someone to judge you.
Why does this make them feel like a less of a person because someone judged them? Whether they realize it or not, everyone makes a judgement about everyone. They just don't always speak their mind and let their opinion of the person be known. So before you even tell someone not to judge you, they've already done it. To me when someone says "don't judge me", I add "insecure" onto whatever else I thought of them.