The one that still cheeses me off most was a teacher my senior year who taught some advanced history classes like History of Modern Russia. On a 30 point test about the privileged nature of Communist Party high-ranking apparatchiks (Read "The Russians" by Hedrik Smith), he dinged me for misspelling the word "privilege(d)"---ALL 7 TIMES I MISPELLED IT!
He likewise dinged me for a similar minor spelling error I made twice. A total of 9 points he took off out of 30, turning what even he admitted was as complete knowledge of the subject matter as anyone in the class, from an A+ to a C F$%king minus--over essentially two freaking SPELLING errors.