What are some bad things about a parent sitting in the class with their bad child?

I am doing an essay on the bad thing a about a defiant child parent coming to sit with them.What are some bad things about a parent sitting in the class with their bad child?
Sometimes having a parent sit in on his/her defiant child's class can be a solid, effective classroom management strategy. Perhaps the kid won't like it (the kid will say it's embarrassing, etc.), but... too bad! The kid shouldn't have been behaving badly enough to necessitate it in the first place-- since this is usually considered a last-resort strategy.What are some bad things about a parent sitting in the class with their bad child?
It Would Be SOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO鈥?Embarrassing