Are audiophiles people of sound prejudice?

Not at all. When something sounds right eveyone with the hearing will agree. As for slight differences in preferances, sure, they exist.

Of course, everybody's ears are different, so they hear differently. This extends to a culture difference in the way we speak and listen. A good illustration of that is the 'British' sound that is often spoken about. I'm from Brooklyn so I know it is all true.

I think any audiophile/music lover thats been at it for a while will go into an audio room for the first time with an open mind, and ears.
There are many that seem to think they know it all and go to an audition with many preconceived idea's.

i think not. the fact that so many people buy and sell, indicates an expectation of improvement, not prejudgment.

how can you prejudge, if you haven't heard something ?

No, not exactly. Different genres of music sound best on different systems. Extreme audiophile's systems highlight the music and certain aspects of that music they like best. This is most apparent in choice of cartridge. Someone who likes female jazz vocals will prefer Grado, while someone who likes Rock will consider Grado a "slow" cartridge, and this continues for the rest of the components.

It's the music we like that determines the gear we prefer.