I have always tried to judge people by what they do, not by how they look or say. When learning to fly I had several instructors. The best of the bunch was friendly, always on time, fully prepared and organised (in spite of the flying clubs unique concept of organisation) and meticulous in his teaching. He was also inseparable from his jeans and T-Shirt. The worst worked for a large and well-known training organisation and always wore a uniform. He made no secret of the fact that he was only instructing while waiting for his airline job and frankly it showed.
As my father used to say, "never forget that spivs and con-men always wear suites".