I'm not sure I agree that once labelled it's always hard to shake off. I think it all depends on the attitude of the children and parents.
There were three boys in my class in primary school who were the "naughty ones" two of them maintained this label throughout high school too because their attitude to pupils, teachers and school was appalling. They were just not nice people to be around.
The third boy totally turned it around though, he was always the class clown but over time became less disruptive rather than more so. He was also nice to people, to fellow students and teachers. School was clearly not high on his priorities but he was never nasty. I saw him in town recently with his partner and two little girls and he has made a nice life for himself, decent job, house and family.
I do wonder though what did he have that the other boys didn't that can make such a difference to someone's attitude like that.