Ref. Crewmember's post.
In a land based hotel, if anybody (regardless of age) messed up a room with (for example) vomit repeatedly, the hotel would be fully within its rights to levy a charge for cleaning. I would welcome cruise lines doing the same. There is no excuse for that sort of behaviour and if cruise lines choose not to pursue the matter, are they not prostituting themselves?
'We don't want to offend guests' is hardly a valid reason to allow guests to abuse facilities.