I have never had it happen to me but I have certainly heard stories.
Ironically, I interviewed the people running the American Girl cruise a few months ago, but I had no idea at the time they were booked on the same cruise as one of our groups.
I don't know anything about the group. but I can't imagine they would have been as bad as some other groups I have heard about. However, we had to cancel it anyway solely because some 'would-be guests' seemed to think it would be a problem.