Many years ago, when I was studying as a teacher, I did a practice stint in a local senior high school. Discipline, of course, was always an issue (as one student said, "It's our job to mess with the student teachers!"), but when I did my review, I said I thought I'd done pretty well, except for one student. No matter what I tried, he was surly and inattentive.
"Oh, well," my reviewer said, "I think you did pretty well. Considering he put a teacher in the hospital last semester."
... OK, file that under "I'm not sure whether knowing that fact would have helped me or hurt me."