Inside the Bookstore:

So how did your student score?
Unless the points here were all for your Number One Pet Hate, there just may be a future for this student in your studio after all. Hopefully though there is a nice list of positives that can offset what's been driving you crazy...but if there's not, then do yourself a favour and cut them loose.
Not a half hour any music teacher would look forward to—plenty of reasons here to consider winding things up.
The money you earn from this student will end up going straight into a therapist's pocket if things continue as they are. Time to start planning the "it's time for a break" speech, or someone's going to eventually discover you sitting in a corner, sucking your thumb, mumbling the student's name over and over...
It's hard to say whether such students are the product of their upbringing, or an unfortunate alignment of suspect genes, but either way, it shouldn't be your problem. In short, why are you doing this to yourself? Go make the call, and reclaim that slice of your life.