This is a recent post from Mr. Hoffmann, in which he notes that, in order to get good service at his bank, he basically needs to act like an asshole. He speculates that, perhaps, that's why some customers act the way they do. Perhaps we only respond well to vitriol.
"We" is a difficult thing to speak for, since there is no such uniformity. But I can speak for myself. I put this in the comments section on Hoffmann's piece, but I want to re-"print" it here, since I do a better job of summarizing my coffee shop credo than usual. At least, I do a pithier job of it.
Make the best coffee you can. What people want to do with it after that is their business. And be nice. It's not that complicated, really. People don't want anything unreasonable from their coffee shop experience. They want their drink, and to be treated in a way that is, at least, not condescending. If they've experienced something other than optimal service elsewhere, and are perhaps a little contentious because of that, it's an opportunity to earn their trust, to show them you do things better.
That's it. Nothing complicated, and nothing that ought to be difficult either. Some people are going to be assholes, because some people are assholes. But no one should feel that they need to be.