Parsifal, I'm sorry you had such a negative experience. As someone mentioned, each group is run by a volunteer moderator or two, following some general guidance. I'm the backup moderator of my local group.
Joining: We ask a few questions when people ask to join - nothing more personal than your city - as a way of filtering out spammers and also making sure people are joining the right group. Because Freecycle works best when members are locals, we limit our membership to those who live in our area: a group of small cities south of San Francisco, along the coast. If someone asks to join who doesn't live here, we will point that person to the appropriate group.
Your offer vs. others: We put each new member on moderation, which means we approve each message before it goes out. We make sure the subject line follows our guidelines (important when people get a LOT of messages every day to sort through), that the item being offered (or requested) is appropriate, and that our few other rules are being followed.
But once someone has posted successfully a few times, we remove the moderation, since that slows down the flow of messages. That means that sometimes an inappropriate message DOES go out to the group. We then write to that person individually, so he or she won't do the same thing another time.
