The art of the cancel

Occasionally you'll need to cancel events.
It happens.
We've all been there.

At times it'll be your fault.
Other times it won't be.

Kids don't respond like you expected/hoped...
You're advertising/promotional material was ill timed/targeted...
You're the victim of a double-booking...
The weather makes the event impossible...

So... WHEN you need to cancel something... How is the best way to go about it?
Do you post a public announcement OR do you cancel quietly?

As a rule, I'm in favor of the last option.

Tell those who did commit, not just apologetically but making it up to them, and those who are in positions of leadership but don't intentionally damage your "brand" by publicly stating, for whatever reason, that the event flopped.