My kids had a good lady teach them a few years ago. My sons had chosen this after school activity quite a few times over the years. Last year the lady quit at the last moment, so they sent the director or the owner for the last few classes. The last class, when I picked up my kid, I noticed that a couple of classmates were crying about it, and my sons look a little spooked too. After inquiring with the kids, I learned that the instructor was extremely upset that the last lesson and was being too rash and even insulting with some of the students in the class. He was rude with some of the kids in front of the whole class and insulted few others. When I asked the teacher about it, he said that he didn't care. In a confrontational manner he explained that he had kids win championships with his company before and that he did not mind that some kids were not coming back or were scared. He certainly did not care that some parents were annoyed. He was not losing business for it, and he could afford it anyway.
We have a "positive reinforcement" policy at school, and we don't call kids names, yell at them or pull apart a quarter of the class and tell them not to come back because they are not worthy. I felt it was uncalled and was particularly disappointed with the inactivity of the principal about it.
We don't have any "review" system at school, so parents just choose within the options and their kid's interest, not about the quality or the type of class. I suppose the children insulted never told their parents about it, a probably just a couple of us approached the principal, she did not care.