Part of it is your own attitude and how you perceive things. The other day I was out driving my Pantera and a nice Cobra passed me in the other lane. He didn't look over, give a thumbs up or anything. Figured it was just some old fart who bought himself a toy and didn't know much about Fords/Shelbys etc. For all I know he could have been a very knowledgeable guy and was just enjoying his drive, and my expectation that he should acknowledge me since I didn't see him first is my own problem
As far as car shows, it's easy to be the expert in your own car, but to show a little humility and curiosity about someone elses can go a long way socially. Even if I know something about someones car already I may ask about it to break the ice with the owner and let them share something they have taken pride in. If someone is just a plain prick and uses their car purely for attention and a slap on the back, chances are I will have nothing to say to them. But you always have to give people a chance before labeling them, especially if you come in as the outsider and they all know each other through the club etc.