Having just slogged through another, particularly heavy round of grading, I had plenty of time to ask myself: "Why does grading suck so much?" I can think of many reasons; call it a case of overdetermination. Herewith a list of causes, ordered roughly from most to least obvious:
1) Grading, because it demands repeating essentially the same task over and over again, bores me.
2) Opportunity costs. Do you realize what great surf we've been having in SoCal? So I heard, at least. I had to grade during the best of it.
3) Our curve demands that I give many low grades. Even if it didn't, some students would deserve low grades. But whenever I give a low grade, I cannot help imagining the distress it will cause the recipient. The grade I give may force a student to drop out of law school, losing thousands of dollars and months of effort. Even when I think a low grade entirely appropriate, I don't like inflicting it on a student. Granted, thanks to blind grading, I don't know to whom I'm giving a low grade. But that doesn't really help very much. I end up picturing the faces of random students, with the dismal mark I've given reflected in their tear-stained eyes.
4) Inevitably, some students will miss some pretty easy questions. You never know why that happens. No teacher worth his salt can avoid wondering, however, if he perhaps failed to teach the topic well. Such self-doubt makes for better pedagogy, but it doesn't make for much fun.
5) Sometimes, very rarely, I have to give a good grade that I don't think a student really deserves. That may be because I suspect cheating or because I think that the student has gamed the system so as to maximize points without demonstrating comprehension of the material. You may well counter that proper assessment of students should rule out those possibilities. Given that we live in a world of scarce resources, however, I suspect that no reasonably cost-effective grading system can avoid such false positives.
6) Grading requires me to spend hour upon hour reading horrible prose, badly written and often barely comprehensible, reeking of panic, desperation, and fear. Exams prove the worst, of course. But even student papers, prepared over months and after several drafts on which I've commented, often demonstrate woefully bad writing. Some people probably wouldn't mind. I savor good prose, though, and feel like a gourmet on a Mac 'n Cheese diet when I have to read a pile of blue books.
Does grading offer any charms? Some of my colleagues seem to enjoy learning how their students did. That doesn't move me, though. For reasons I won't get into, here, I make a point of trying to remain ignorant of which students get what grades.
I will say this for grading: If I didn't do it, I'd lose my job.