I think your experience is very typical, if not a wee bit better, than most uk school kids. I am in my third year teaching in a nice middle class area yet there are still huge behaviour issues at my school. One kid in year 9 burnt down the toilets last term...! I hear many similar reports from my colleagues in other schools across the area.
I would make some disagreements on the inspections. Schools now get far less notice. Its just the night before were told ofsted will come. Also, if a school was found to be taking trouble makers out i imagine they would find themselves in special measures very quickly.
Also, I'm not sure how a school could game assessments which have external examiners? With coursework that could be an issue but thats all but eliminated now.