I cut people in the service industry a tonne of slack. I don't make special requests, I'd never send back food unless it would be harmful to eat, and I tip like I'm made out of money (I'm not). Why do I do this? Because I know I wouldn't last 3 minutes doing that person's job. I have a low tolerance for people as it is. Throw me into a situation where I have to interact with the great unwashed at a constant rate AND smile while doing it? That story ends with a police presence.
BUT...I do require a certain standard of service. I mean how fucking hard can it be to put together an egg mcfuckingmuffin? English muffin, ham, egg, cheese, English muffin. We're talking one step above buttered toast here. The egg mcmuffin is about the only thing I Iook forward to while I'm on the road and to bite into one and realize some slack jawed teenager couldn't be bothered to add the ham to the equation ruins my day. RUINS it!
Look, I know your job sucks, I know working at mcdonald's does nothing for your social standing, but that doesn't mean you can't do your job with a minimum of pride to match your minimum wage. Thanks for listening and thanks for not spitting in my food.