Conspiracy Theory!

Let's examine a fascinating habit of the human minds, the need for pattern recognition where this is no pattern. What is the lure of conspiracy thinking? Certainly there is no denying that various conspiracies abound. And suspicions are sometimes valid. But how do we know when we are going overboard and seeing conspiracies where their likely aren't any? Can we articulate a criterion for valid suspicion? (Remember, just because your paranoid doesn't mean they aren't out to get you)