I don't have , and I'll never have a facebook account.
But a private event invitation sent via facebook, shoudn't be private ?
I know, facebook != privacy. But it will be the same thing , if I sent 30 invitations email for my birthday party?
Even I don't care if everyone in the world knows that I plan a party. But come on, if the police can find the party with facebook tag "all-night" , they are able to read that's just a BBQ party. And their was only 15 guest that accept the invitation.
Ok let do a event : A traffic jam party: more than 100 person, music ( I'm sure that at least one person listen music in his car), etc.