well, i think its a myth... I dont know hows in britain but surely in poland there is a load of lazy and bad students either ;)
Polish girls I know with children are learning English practically fluently within a matter of a few weeks and I have not met a bad behaved Polish child, they are absolute angels, they know all of their manners, they are chatty and friendly and clever. They do not know any swear words and they don't want to shove a firework up one of my dogs' ar*ses ha ha ha. As you can tell I've met some adhorable little English kids :-)