I had a friend sell tickets to today's game. He posted them on Craigslist without covering the seat location and barcode. Someone somehow translated that into a stubhub ticket advertisement. The people that bought them on stubhub went into the game before the people my friend sold them to in person, so the the legal sale became worthless.
It's going to be somewhat easy to resolve considering the audit trail behind it all, but just something to keep in mind.