I have been pulled off before, but none of the times memorable.
What I have seen is the opposite. Some of the most amusing stories we have at the airport are when an agent (or Manager) gets stuck on the flight the door closes. I have had it happened to me. Most of the time the Flight Attendant recognizes someone is on that shouldn't be. There are times though that the flight pushes back and gets ready to taxi. The cockpit crew gets a big kick out of it and calls back to see if we are missing an employee. The truth is we are always tempted to tell them to take the employee with them so we don't ruin our OnTime performance. We can always have them sent back on the next flight.