One of the least happy times for a teacher is grading. Beyond the raw score there are many external factors: the student needs an A to keep coming to school because of a scholarship, the department wants to look better, the college wants to keep students, student feelings which are related to teacher review sheets are also part of the mix. What do we end up doing, grade inflating.
Owen Strachan has a couple of interesting articles on the phenomenon of grade inflation and the kind of mindset that goes with it.