herbie- I've noticed that in every class at school there is always a kid that everyone will blame for things even if they had nothing to do with it. It's hideous, particularly by secondary school as often these kids will have zero self-esteem by then. I saw this in operation quite recently in a school near here, with two different kids. Kid 1 came to my children's school from this other school in year 5 because he was not being taught with his classmates, was effectively on permanent internal exclusion. The teachers and all the parents, as well as the children were all blaming him for everything that went wrong. When he left, the scapegoat became another boy, who left the school 6 months after the first- the parents were furious, as they watched their child take the place of the first within weeks, and not of his own doing.
The first child was very bright but very much ADHD and easily riled. The second was also extremely bright but on the AS spectrum and would insist on putting everyone right, including teachers, when he knew they had made a mistake. He was not Mr Popular at that school. Both these boys thrived at my children's school, and the ADHD one went on to top sets in a high performing comprehensive (from full time internal exclusion, quite a leap). The other boy's parents decided that he would be better off being taught at home, but he left after 18 months a changed and much happier boy.
Until your child is at receiving end of this crap, or you see it at close quarters, you may actually not believe it possible.