Isn't Professor Binns a ghost? There would be the extra added issue of actually getting him to leave, without an exorcism. Plus, I believe that Rowling actually says something in the books about how no one else wants the job (which makes me think she hated History as a subject in school). And, he's probably cheaper than paying a living person to teach the course.
Ebony the Black Dragon
http://ebony14.livejournal.com
"Good night, and may the Good Lord take a Viking to you."
Ebony the Black Dragon
http://ebony14.livejournal.com
"Good night, and may the Good Lord take a Viking to you."