A teacher is a person who helps students to acquire knowledge, competence or virtue. Informally the role of teacher may be taken on by anyone. But sometimes being so good he/ she is not liked by everyone.
All teachers have once been students, and many times they want to help and be more effective. Teaching is not a rosy job. Sometimes you have to confront the difficulties that arise in the learning process.
What I really detest in a teacher is that he does not know where the limit goes between a student and a teacher. A teacher who shows moral strength knows that a student is in a dependent position and does not use her sexually or abuse his position in other ways. A teacher who constantly update his knowledge and is a good example for the student and thereby elicits respect. It is a shame that I have to write these things.