I had a similar situation in ATL. New gate agent. This gate had the GIDS(the screen showing info, among it, a standby list). So I could see exactly where I was. I was number 1, and there were 8 open seats. The next departure was to like BNA and there were a bunch of people(revenue pax) for a later flight coming up and bugging the gate agent to standby for the BNA in an hour, but he was trying to work my flight first. Well, he boards everyone. It's been a few minutes. I contemplate, to bug or not to bug. I wait a few more minutes, and then in my softest nicest voice, approach and ask if the plane still has 8 seats like the screen says. He says, "sir, give me a minute, just let me get this flight closed out and then I'll answer your question." I told him my question was about the flight he was closing out. I told him I'm a nonrev and the screen shows plenty of open seats, but it's been awhile since he boarded everyone. He told me that the plane taxied out a couple minutes ago...gone. He was upset with himself and actually offered to buy me lunch. I was of course frustrated, but I mess up my job from time to time.

The next flight was full, and the next one. I actually got on a plane home about 4-5 hours after this incident.

Most agents are honest and do a great job, but that stanby list can be cleared out of order, and some agents do that. Never leave the gate. I've seen agents tell a nonrev that the flight is full, and to go back to the ticket counter to list for a later flight, only to call their name 5 minutes later, label them a no-show, and clear their buddy pass.

I've never printed a standby list at the gate though.