Purely inexcuseable, hm? What are we going to do, kick out every rude patient? Not happening!
There is no reason to take offense to patients initial attitude. It's got jack to do with you. So, get a thick skin and don't worry about it. Just concentrate on the goal of having as positive an interaction as possible. Learning to manipulate people's behavior (including our own) is a big part of becoming a successful clinician. Even if you don't want to be a clinician, the whole "I shouldn't have to put up with this crap" attitude doesn't make the experience easier on anyone. You have to put up with it. Deal!