If the hive is too mean to the point where the bee keeper doesn't like it then the course of action is prety much a no brainer. You gotta do something, either requeen, split or combine the hot hive. I always rate my hives agression on a mental scale of 1-5 with 5 being the hottest. One of the worst hives I worked lost it's queen and gave me over a dozen stings during teardown. Got another half dozen putting the hive back together after running away for a few minutes. It is pretty funny now but not at the time.