I had this one math teacher in high school that everyone hated. She was very shrewd, a tough teacher, loud and mean to all the kids that tried to kiss up to her or cry for good grades. She was small and fiesty.
She was always good to the kids that she thought were 'bad' kids though, like they were her sons. I was a bad kid in school and she was nice to me and my friend. probably the most impactful teacher I had in my life.