We've all had bad teachers, but some are much worse than others, and there are ways to handle them that work well and that will benefit you, instead of just making more trouble.
If your child has a bad teacher, the first thing you should do is talk to that teacher. Be open to discussing any issues with them. If you get nowhere, you might want to talk to parents whose children had that teacher in the past. They might have some ideas about action you can take, but be discreet.
Next, talk with the guidance counselor. He or she may be able to do something about it, especially if there are other complaints. If nothing changes, you can then register a written complaint with the school or the district. You should also assess the teacher objectively. Don't assume he or she is a bad teacher based on what you've heard from others.
You can also sit in on a class. If there is a rule against it, try to get a waiver. Going to the principal of the school or to the district should be a last resort.