As beloved as the Harry Potter franchise and its many Hogwarts teachers are in our hearts, J.K. Rowling is an astute writer who knows better than to write flawless characters who never grow or change. None of her characters are perfect, even the headmaster, Albus Dumbledore himself. In fact, he may be the most flawed professor at Hogwarts School of Witchcraft and Wizardry. That's a good thing, since perfect characters would be boring, but some of Rowling's writing makes us wonder exactly what she thinks makes for a good teacher.