I get what you mean- I belong to a horse forum with a small community (About 25 active users). It's where all of us who have been on Yahoo! for a long time went after the horse section became infested with trolls.
The person who made the forum has been on Yahoo! for approximately 6 years. She, as well as the other mods, have been great about keeping unwanted people out. And all of us on there have been on Yahoo! for years. We know each other well enough from that that it is easy to trust the people on this forum. Two of them are my penpals, and were before I was on either of those forums. It doesn't mean I will give out my name or address though.
It's about finding a balance of how much you can give out about yourself.