Having just graded another midterm, I realized something.
My favorite part of grading is when I ask a question that I know is difficult (but meaningful), and I see a student just totally nail the right answer on the head. It makes me feel... validated, like here's someone who was paying attention, here's something that I was able to teach.
My least favorite part is when I see an answer that's totally unintelligible, like the student was answering a question that I didn't ask, and it's clear that they either misunderstood the question or else that I'm misunderstanding their answer. On the one hand, I teach game design, not communication, so if the student understands the question and has the right answer and just has difficulty communicating then I feel bad about taking off too many points for it. On the other hand, I can't justify giving points for an answer that I don't think is right. So, I have to dock the points and hope that if I'm wrong, the student has the guts to call me on it (which actually happens a lot less often than I imagined it would). But I just hate the uncertainty.