Hands down worst professor I've ever had, anywhere, was a graduate of either Yale or Princeton. Got her masters at Purdue. I cannot begin to explain how poor of an instructor she was.
In fact, the guy that sat next to me actually stopped her in the middle of class (after she wouldn't allow us to ask her why she was doing a fundamental calculus formulation incorrectly), told her she was completely wrong on what she was doing. She asked him what part.
He stands up, goes to the board, takes a piece of chalk, and starts at the left board, draws a line across everything she's written to the far right board, and says "From there, to here, nothing you've done is right unless you wanted to confuse the class or make us think you're unqualified to teach."
She wasted 30 minutes teaching the class the incorrect way to do something and never got it corrected completely. When I dropped the class, I wrote a scathing note to the head of the math department on why I was doing so. Still gets me hot under the collar to think she had a job as an instructor.