I think there are also cool teachers in the sense that he presents everything clearly and thoroughly and in an easy-to-understand manner. It must be noticed, though, that most adolescents may not "appreciate" such teachers!
I remember a few teachers in high school that I consider cool: one teacher always called back to basic foundational principles in 5th Form (equiv to US high school Sophomore) chemistry such as moles, empirical formulas, etc when we got stuck. He also extended the teaching materials and included something about acid-base concepts that were not examinable until 7th Form (senior) but which helped us immensely in understanding 5th Form materials (of course he didn't set any tests on these extension materials). Another teacher in maths taught all the common tricks in problems such as solving (2x - 1 = 2x + 3).
Of course, bad teachers are those that actually refuse to really teach anything, those who actually thought he had gone over a topic but in reality hadn't (I had one teacher like that when in high school - and it produced confusion in the class). I'm sure that most of the students in Mr Bennish's class would consider opinions like mine as from nerds.
I was also one of those nerds who considered "cool" those teachers who could teach their subject matter in such a way that I could both understand it and feel motivated to learn it.
I had several excellent, many mediocre, and a few flat-out bad teachers in my academic career.
To this day, I cherish the memories of those teachers who really inspired me to learn.