And I predict this one will too and it will probably be sooner rather than later. Get ready for a mugging from the 'double-blind everything sounds the same gang.'
Rather than try to prove that cables are a ripoff, the question to ask is, why woudn't they be?
The thing is, if I was a not-very-capable manufacturer looking to make money out of audiophiles, I would choose cables as my ripoff of choice:
(a) It's very hard to make one that doesn't work in the simplest sense (not shorted out, not broken)
(b) No one expects cables to meet any sort of technical specification beyond the simplest requirements
(c) It is well known that people 'hear what they want to hear', and respond to the look of equipment, claims of exotic materials, special 'weave', advertising and so on. Audiophiles seem not to believe this.
(d) There is no scientific rationale behind claims of the sonic properties of cables, and the audiophiles don't even expect there to be one.
(e) There is no requirement to provide any proof whatsoever that your cable sounds any different from a piece of ordinary wire. Chances are high that the punter will fool himself into liking it - so high, that you can even offer a money back guarantee, pretty safe in the knowledge that it won't be used. (You can even mention a 're-stocking fee' in the small print, but the customer won't care in his eagerness to take delivery of this small package that's going to change his world for only $500).
(e) Even if the punter fools himself into thinking he doesn't like the cable (these things can occasionally go either way dependent on the weather, traffic etc.), just tell him that it needs burning in. It's almost certain he will begin to like it, believing he has invested time, effort and creativity into shaping it to his own tastes.
(f) Real electronic equipment is hard to build, and involves safety approvals and so on. Unlike cables.
As you shell out real money on cables and other 'tweaks' you should be asking yourself why the manufacturer
wouldn't be scamming you. Do you really think that they have magical powers that can imbue a cable with 'presence', 'soundstage', 'openness'? Why on earth would you think that? Do you really believe that the shiny-suited salesman, or the multi-doctorate proprietor of the company (they always are aren't they?), really can hear the difference between their cable and a bit of old screened cable? Of course not! What makes you think they can? Do you make a habit of giving your money away to anyone who makes up an imaginative story? When you've bought your cable, why
wouldn't the manufacturer start laughing uncontrollably, rolling around naked in piles of your cash? Because he's got a really difficult problem to attend to? Turns out his next generation SPDIF cable has a lack of focus and bass rhythm? Of course not! His only problem is that other manufacturers also know the secret of audiophile cash. But hey, there's plenty of it to go round...