I would say I do have encountered numerous nonqualified instructors, with respect to higher standard of teaching. The most recent one was in a university extension class with unsupported environment.
To refresh my knowledge in statistical inference, I registered in a university extension class, most of whose teachers and students are industry practitioners. During the course, we were required to do eight homework assignments. Believe it or not, I had received neither grade nor feedback on any of the eight. The only thing I received was the automatic message from the University server about the on-time submissions. In the last lecture of course, there was finally a handout of the so-called solution sheets and a short period of homework reviews. At that time, I believed most classmates already lost memory on details. One can imagine what happened. The instructor basically spoke to himself.
To be worse, the instructor was often evasive to students’ questions. He was a program manager in a private company. Despite having a PhD in math from an Ivy League university, I felt he behaved more like a politician. He usually gave answers as vague as possible to tougher questions. The most typical response is “It depends”, without adequate elaborations. When being pushed further, he would start to divert.
What could have been done differently? The root cause could be that the instructor lacked of enthusiasm in teaching. He needs to change his mentality from deal making in corporate world to motivating people in classroom. He should have communicated more with students. The only message broadcast from him was the syllabus when the course was already in its fourth week. His indifference to teaching as an instructor might eventually damage his reputation.