I can't say I've ever found them particularly badly behaved. I can count on one hand the number of incidents of bad behaviour I've seen in as many years.
I'm not around the area or on the bus at school closing time, in which case I might have a different view - but I do remember how we were at the same age, in one of the area's less delinquent high schools.
So I don't really go in too much for the 'o tempora...' stuff.