Aggressive know it all salesman

Why is it that of all the things I have ever bought - fast cars, nice watches, nice clothese, good food - it is the audio salesman that is the snootiest know it all snob of the lot.
I don't adertise my knowledge of audio, which whilst not encyclopeadic, is not that of an idiot either. I recall calling up one supplier to just ask about a pulley for a turntable, and before you know it I got lectured about why DC motors are better than AC. I ended it saying that: I have an ongoing project; a very good battery powered DC turntable as well; two superb DC direct drives, and an idler drive project on the go.
This isn't something to level at all people in audio, I found the guys from Absolute Sounds i nthe UK very approachable and enthusiastic - they weren't the 'audio snobs' I either feared or expected. Likewise it is lamentable that Les Wongs Walrus Systems is now defunct. But we all know the dealers and suppliers out there that are such idiots - bit like the 'haughty' french waiters of yesteryear.
When I want to buy something specific, or if I was just enquiring I really do not expect, nor appreciate being spoken to like an idiot or a child, nor do I think it helps the industry when the people in sales think that you almost hae to be part of a kind of 'in the know club'.
I would appreciate your thoughts on this
Some sales people are great others are just ok its up to you to know which is which.
It's worse when you're treated to the snooty attitude by young junior salesmen when you knew more than they did before they were born, and whose exposure to music only extends to radio talk show jocks, Diana Krall and Jazz at the Pawnshop.
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Because the average audiophile customer is so poorly informed.  For a high end sports car, the customer is usually a "car guy."

I deal with know it all audiophile salesmen by asking them where they got their engineering degree.

If they have a good comeback about not needing one, I ask about their degrees in bioacoustics.