Try giving better than you receive.I certainly don't go in with a sourpuss attitude. I'm always nice to workers. My natural charm usually does it.
But oftentimes it depends on how they present themselves. If they're dealing with me as a human, then I deal with them on a human to human level. If they're dealing with me as a representative of a cold, bloodless corporation, acting more like automatons than humans, then that may be a different encounter.
Then you might....just might fare as well as I do.