I agree! I've worked with a few beginning singers, and I have found that if they really want to sing, and they become involved in singing (choir, for example), and listen to good singers A LOT, they will progress very quickly. But I agree with you about teachers. You have to have a teacher that has the "self awareness" as you put it, to recognize their own shortcomings. They have to be able to help you improve your voice, or direct you to someone who can.