I don't know if this stops that, but one thing I noticed is that a lot of people have their statuses set to share to friends-of-friends, or to everyone. For the most part, this is bad (unless it is a business's page, where they may want everything
shared to everyone).
Anyway, here is how to change the default to be Friends Only.
1. Go to your privacy settings
2. Set it to Friends Only
Now, when you post something, it is set to be viewed by friends only by default.