OK, so how can this be filtered? I wonder how much effort they will put into making the billboards appear "real". If they don't care too much then it may be p

OK, so how can this be filtered? I wonder how much effort they will put into making the billboards appear "real". If they don't care too much then it may be possible to detect them automatically. Or maybe the best approach is to write a general filter that recognise and filters billboards whether they are modified or not.