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
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2. Set it to Friends Only
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Now, when you post something, it is set to be viewed by friends only by default.