The worst professor story I've heard happened to a friend, who was called stupid by an English professor for (if I recall) something pretty basic, like asking for extra some help.
Of course, I was an engineering student, who started at IIT, where there was one tenured faculty spot in all the humanities department (which grouped, as I recall, English, History, and foreign languages).
Some of the science, engineering, and mathematics faculty were decidedly odd, like the physics professor who started the semester by jumping up on a desk and proclaiming his name, and never erased the (double-hung) blackboards during class, instead relying on multiple colors of chalk. One was a fan of Velikovsky. Another would smoke while he taught, lighting a cigarette, taking a puff, and then standing it on its filter, never touched again; instead, he would repeat this with a second cigarette.