To me, it depends on the person running th game. If its someone I know, and I understand why they've had to cancel - I'm far more understanding than if Joe Schmoe says "Huge Game in my backyard, 12 acres of bunkers and bunnyrabbits. Preregistration 30 bucks, at the door 40 bucks". I don't know Joe Schmoe, I don't trust Joe Schmoe.
If Younblood, John Boy, Terror Management, etc put on a game, and I can commit to it - I'm far more likely to preregister, and far more likely to be forgiving when shit happens. Like others have said, I've put on games, I know that all too often, game promoters are stripping their food budget in order to pay for event items, and sometimes there just isn't enough money to secure the venue/pay for props etc, and if not enough people pre-register, it just can't happen.