I don't really think that roadies are all that snobbish. I think that what comes across as distain may just be "focus". A lot of "racer-type" folks are out riding with a purpose --- to get fitter, faster, and just better. If you sat around with them before or after a ride, you'd probably get a better impression. The fact of the matter is that when you're racing in a car there's no opportunity to talk to the other drivers. On a bike, it's a bit different. A lot of folks seem to expect to talk to other cyclists as they pass each other. Do you expect the same thing from other drivers?

What you say about amateur car racing (assuming that's what you were talking about) applies equally to amateur bike racing. Racer's don't really care what you're riding. Most of them only care that you're out there trying your best, too! You will, of course, get more respect if you can finish somewhere other than OTB.