I have had a couple of professors who were horrible bullies. I no longer take classes at that college, and am taking credit courses somewhere else now. It has worked to switch schools.

Also, it is an unfortunate fact that professors can have biases for and against certain students. One of my professors seemed to hate older students, but she would give the younger students a lot more help and support. The bias was so obvious that everyone talked about it.

Some professors would try to discourage students from their chosen career path, saying things like "you aren't cut out for this". Often this assessment was based on meeting the student only one time. The more competitive that the academic field was, the worse it became. Many students graduated and did well in their chosen profession in spite of their professors telling them they would never make it in that field.