Since I started teaching, I've really only had one or two run-ins with disgruntled students. (Lucky, I guess!) Today, one guy (who frequently misses my writing class) wasn't doing the assigned activity, so I went to take a look at his essay. Turns out he had basically written me a note accusing me of failing him out of spite last semester; ergo, he explains, he chooses, frequently, not to come to my class. And he doesn't come because he isn't interested in it, he writes.
This really took me by surprise, and after thinking about it for a while, I realized that what bothers me is not that he doesn't like my class, or that he doesn't come to it (I mean, that bothers me a little, but it's his choice), or even that he thinks I failed him "on purpose" (which is impossible, since I don't know whose exam I'm grading when I grade the finals). It's that he waited five months to tell me that he was unhappy with his grade and the class. I told him that if he had a problem with his grade, I would have been happy to talk about it -- a few months ago, which might have prevented all kinds of problems.
I have to ask myself, could I have done something to prevent this? I try to make myself accessible to the students, but from the beginning of the year, I've been of the mind that one-on-one time is impossible, since I have a total of about 400 students in the 9 classes that I teach (only 4 classes are writing, though). I encourage questions, I give students my email address and QQ number, and I give specific, targeted feedback on essays -- but I can't make students come to me if they have "issues," and I sometimes just can't know there's a problem.
At the end of last term, I made a tentative plan to have one-on-one meetings with the writing students whose scores were consistently low or who didn't turn in assignments. I scrapped it (wrongly, I think) due this misguided "oh, there are too many students" belief. Now I'm wishing I hadn't.
Incidentally, the other run-ins I've had were:
1) A student refused to get up to do a group dialogue when I told his group to go sooner than he had expected. Eventually he calmed down and did his thing a few minutes later.
2) A student was talking continuously and loudly over another student's speech -- which was the final exam. I ended up yelling at the kid (who really should not be an English major, but that's another story) and completely spooking the one who was giving the speech.