It's part of the religion for the expensive ones.
It also gives them a way to tell the customer not to return them right away when they don't hear the magic. It may not sound any better now, but give your brain time to burn in the idea that these must be better, and sure enough...
Those who buy cheaper, competent cables, buy them precisely because they know they are adequate for the job. They don't need to listen with a dose of snake oil.
Sensible re-sellers should have the cables (if required) burned-in for the requisite time -before handing over to interested listener's.
When I had my store, I did this regularly: If interested, take (cables) home (over the weekend) and return them with your HONEST opinion.
I stressed if no differences/or very little differences were observed to inform me of precisely their thoughts. I went out-of-my-way to assure them if they returned the cables laughing (for good/or ill) i would not be offended: I was just looking to gain further listener consensus (and I was).
In no way did I expect them to purchase the cable -just wanted them to experience first-hand.
Near all of the interested listener's (9/10) were nothing short of astonished at what they experienced; no one was breathing down their necks, nor were they rushed in a noisy environment -they were at home . Many had their wives/children;;s and friends chime-in to make sure they weren't "hearing things " lol. ALL, were surprised -and enlightened.
Sometimes, it's both practical an sensible to lean on use some collective wisdom when engaging in into such territory, but most importantly an open mind -and the comfort in acknowledging and appreciating the sold merits of honest feelings/listening observations that I suspect can be helped along by decidedly non-audiophile type listener's. And then come to the realization/understanding that there exists an entire psycho-electrical world/reality 'we (science) poorly understands -yet will slowly unravel.
Yet, there's no point/need waiting for that "proof" is there? It's been my experience that some listener's are inherently ill-equipped to sense, feel or appreciate nuances and thus desperately demand something physical; anything (a graph -numbers, data, spec's) that shows it is, or isn't.
Such 'listener's are simply out-of-their-element (displaced) when it comes to appreciating the dimensionality, range, color and fidelity of premium, high-resolution sound reproduction.
peter jasz