Doesn't always work especially when the agent is a known douchebag and there are plenty of them.

Back when I used to j/s to work, there was a certain gate agent that did not like pilots for whatever reason.
When he was working, I always missed the first flight I was trying to get on. Always.
When he wasn't working, I got on the first one.
Amazing how that happened.

The best day was the day I caught him in a lie.
He tried to tell me the aircraft was weight restricted that day. Little did he know I flew the same Boeing aircraft. I wanted to know what the problem was since the aircraft was taking a weight penalty in excess of 50,000 lbs for a 900 mile flight. I got on that one.