I deplore this era of cheap flight for all and am a fierce advocate of compulsory IQ tests before anyone is allowed to buy an airline ticket.
Are you suggesting intelligent people aren't capable of causing trouble? Some of the worse passengers I've dealt with weren't "chav scum" but people who really ought to know better. And it's precisely because they think they do know better that they behave the way they do. I'm sure you know the sort I mean - white, middle-class, "I know my rights", Daily Mail reading, Merlot-glugging pompous asses.
I actually prefer to deal with, shall we say, the lower end of the market because firstly they don't think they're better than you and look down their noses at you and secondly you can often have a good old argument with them without them taking umbrage!