You guys are looking at this wrong. There is a vast middle ground between Disney service (which to be blunt, is not at all what it used to be!) and the person you are dealing with acting like a grade A jackass that should be put out of my misery, not to mention theirs. There is a middle ground right about in the middle of their that most companies and employees see as the expected and required level of service.
However, there can be variations, and it depends on the actions of the consumer.
Three Scenarios:
One) Bob walks up to the Amlounge counter, barks "Coke!" while thrusting some money at the attendant. The attendant silently grabs the money, plops the can (of Pepsi, of course) onto the counter, and makes change. He doesn't say a word. The customer looks at the can like it is some kind of alien from mars, and barks "I said COKE!". The attendant shrugs his shoulders, and moves on to the next customer, leaving Bob to stew in his anger.
Two) John walks up to the Amlounge counter, and looks at the attendant, and says: "Coke, please." The attendant informs him of the price while getting a can of Pepsi out of the counter and filling a cup with ice, placing them on the counter. John says "You don't have coke?" while handing the attendant the money. The attendant says, "Sorry, sir, we don't.", and John walks away not so happy, but satisfied.
Three) Mike walks up to the Amlunge counter, smiles at the attendant, and asks "May I have a Coke?". The attendant locates and holds up a can of Pepsi, saying "We only have Pepsi products, that ok?" Mike hands him the money, smiling, and says "Well, I prefer Coke, but this will do nicely." The attendant give him the Pepsi and a cup of ice. Mike thanks him, and the attendant says, "No problem."
All three are acceptable. It would be acceptable for Bob to get any of the three responses, although he doesn't deserve any but the first. It would be acceptable for John to get either the second or the third. Mike could also get the second or the third. These would all be acceptable.
What would be unacceptable? Mike or John getting Bob's response. By acting like a jerk, Bob has denied himself the right of getting pleasant service. He still can reciecve it, and a really good employee would give it. But he is not longer entitled to that level of polite response.
What would be unacceptable for Bob?
Four) After hearing Bobs request, the Attendant looks at a wall of Pepsi, and says "Nope, ain't got that." Bob, fuming, says "What about all the ****ing Pepsi?" The Attendant looks at it again, says "You asked for Coke, we ain't got no coke." Bob says "Pepsi, now." The Attendant grudgingly takes Bobs money while tossing him a can of Pepsi. Any time that Bob comes back to the counter, the attendant is on break, amazingly enough.
Thats unacceptable behavior on the attendants part. Bob might deserve it, but its still the attendants job to sell Bob food and drink.
Personally, if the attendants used as an examples were in fact one attendant, and worked for Amtrak, and I would like having him on my train. Someone who is acting like a jerk deserves only perfunctory service. I don't care how much you pay someone, or how much you are paying for a level of service. Acting like a jackass nets you a deserved amount of less niceness from the employee.
Personally, I'd rather the attendant take out his irritation on Bob then let it stew until Mike comes back and asks an irritating question involving lateness and gets read a riot act he did nothing to deserve. Or until he gets home and reads a member of his family a riot act they don't deserve.
There is even less excuse for treating service employees shabbily than there is for them reciprocating.