Well, my kids are long out of school, so my answer is from the past.
I don't believe in bullying behavior, but I was never afraid to point it out if a teacher was out of line. There are bad teachers who need to be called on the carpet. Once, the parents' group I belonged to helped get one such teacher fired for handing out busywork dittos while he sat with his feet on his desk studying real estate textbooks.
Obviously, teaching was not what he wanted to do, and he should never have been in the classroom at all.
I have also run across teachers who berate and bully kids, and I'm not above letting them know in no uncertain terms that as a taxpayer, THEY work for ME..and I'm not paying them to treat my (or anyone's) kids rudely! I don't call that bullying. I call it, "telling it like it is."