Ever play the telephone game? You say something to one person, she repeats it to the next person, who repeats it to the next person ... ad nauseum. By the time the message reaches the end of the chain, a statement such as, "Man, I could really use some Chipotle right now, but I'm blogging instead," becomes, "I've got a chicken in my head."
Reliability. It's one of the reasons why hearsay is naughty -- except, apparently, when crackheads phone in their testimony to a third party who then prepares a sentencing report.