From another thread about getting impromptu upgrades:
Which I do too. But we've all seen the folks who take the opposite approach of yelling to get their way. So does that actually work? Does the squeaky wheel get the grease?

The only time I even get perterbed at a gate agent (but opt for the eyeroll rather than getting pissed) is when they are just being incompetent. With phone agents you can hang up and call back. When a gate agent doesn't know how to check for available aisle seats, its a little rude to move over and talk to the guy working right next to him.

But in situations like weather and mechanical delays - things that are completely out of the control of the agent, what good does screaming do? Is someone really going to work harder for you to get you on a better flight with a FC upgrade if you're making their life miserable?

I've got to assume that screaming works, otherwise you wouldn't see people doing it so often. I just don't understand why it would work.