The best professors I had were those that had worked out in the business world before coming to teach. They taught what you really needed to know rather than all the fluff most of the classes are filled with. The worst were those that loved to derive equations every class (Physics Dept) and confuse you. My Physics II professor was the worst of the bunch. He would derive equations the entire class period and then give you a ton of homework that he had not explained how to solve! I have never used any of what was taught in that class for a single second of my job.