I was recently on a DL flight from DCA to TPA. I got upgraded to FC and was sitting next to an employee doing a non-rev. On the short 2 hour flight, he managed to drink 4 JD and Cokes (flight was at 9am) and spilled another two on himself and the floor. Amazingly the flight attendant didn't cut him off and just kept feeding him booze. He wasn't loud or too annoying....just a sloppy early morning drunk.

I also non-rev on US Air a lot and as a rule of thump I'm on my best behavior, and then some. Always polite and patient with the staff, wait to be called for clearing at the gate, low maintenance in the air, etc.