One day at work a friend came by my office with a smile on his face and told me something funny. He had just been interviewed by an FBI man who was investigating someone for a security clearance.
My friend had been listed as one of the "six people who know you well" (or was it "eight"?), so he answered all the agent's questions.
When the interview was over, my wise guy friend asked the agent why he even bothered to check personal references when he knew perfectly well they were all good friends of the man being investigated. The agent explained that although the references might be good friends, they would often provide leads to other contacts who were not good friends.
Then the agent added: "Besides, you never know who your friends are."
gpl