Perhaps.  Perhaps they perceive it to sound better even if under scientific conditions they couldn't tell them apart but if they want to spend their £4K on that then I don't have a problem with it.

Also, whilst I agree with you in some regard about snake oil vendors they wouldn't exist if people weren't buying it.  If someone is mug enough to pay thousands of pounds for a cable that's no better than a £50 one then they only have themselves to blame.  OTOH if they think they hear thousands of pounds worth of improvement then who am I to tell them how they should spend their money?

As an example, many people would regard the "green pen tweak" for CDs as pure snake oil but in my experience it definitely works so I'm happy to part with my cash for it regardless of what the science says.

Michael.