Well I never had anything as serious as DMKA, but my Physics 12 teacher was inexperienced (so he knew next to nothing about the subject and he made some overspecified questions(there was too much data, so you could get different answers) and he would also give super unclear questions so he could mess up people he didn't like because no one could tell what he wanted) and mean (he actually was more a favortism type teacher, if he liked you, you would ace all the labs and subjective questions and he would mark easier on the other questions. If he hated you, like he did for me (I have no clue why, then again it must have been because I kept on correcting him, but I mean, it isn't my fault he made mistakes) he would totally mess you up on the above things that he gave basically free marks for to the people he liked. Plus he was the only Grade 12 Physics teacher in my school so you couldn't switch. (pretty sad) Since this was B.C. though (where we have provincial exams), when the exams came along everybody he liked did much worse on the exam then on their school mark and everybody he hated did way better on the exam. I think the school noticed and finally got rid of him.