I had no idea this was true until a buddy of mine who I play hockey with started putting super offensive notes on the payment, trying to trigger someone since it was a hot debate after one of our games if this actually occurred. After about five or six of these, someone did in fact contact him first via email, then actually called him and asked him to explain the notes and yes they do monitor these and yes, if its really suspect, the feds will be notified.
Which then begs the obvious - if you're buying drugs, then don't put you're buying drugs or paying off your bookie.
I guess it's law enforcement on the honor system - when you do something illegal, you're expected tell the police-monitored feed that you did it. We assume that no one is so unethical that they keep their illegal acts secret.
For extra credit, let's put this stuff on the blockchain. Crime is solved!
Which then begs the obvious - if you're buying drugs, then don't put you're buying drugs or paying off your bookie.