Keep a history of each member's rsvp's. Keep history of who replied 'yes' or 'no', and then changed it. Anyone who cancels the morning of an event, I consider as a no-show. It sabotages the usability of certain venues once the rsvp's drop, and by keeping track of who rsvp'd "yes" three weeks ago, and changed it to "no", the morning of, helps me rid my meetup of flakes. We're adults. I don't think every site should be forced to expressly state a no-flake policy.