What makes a teacher successful and who should be the judge of that success and why?
I think a teacher's success starts with the teacher's goals. A good teacher understands herself as an individual and understands how to make attainable goals. Without goals a teacher leads an aimless career which may have small successes, but not overall satisfaction.
I think a successful teacher learns from failure but does not dwell on it. It is hard to stay confident when becoming humble but the successful teacher sees the overall success from the goals she has attained and the success that will come once the failures are cured.
Only the teacher herself knows how successful she has been. I don't think success is always one hundred percent visible by the outside eye so it is up to the individual teacher to make sure she is successful and attains her career goals.