I can't remember where I found the news article, @Elliot131 , but I did read a month or so ago that, yes, guests do this (there are blogs/sites that suggest it to them), but if they try it a second time, their account is suspended. The system puts up with it only once.
That doesn't help individual hosts who are their first-time victims, but since chargebacks on credit cards are possible, I'm not sure what else Airbnb could do.