Who says cables don't make a difference?

While there could be a difference, there is some bad physics used to sell some cables. For instance, skin effect and the claim to need to mitigate it with litz or ribbon construction. Skin effect is alleged to increase the resistance of speaker cables by diminishing the cross sectional ares of the cable conducting the signal. All this is true, but how much does the signal get attenuated by the increased resistance at 20 kHz? This can be calculated and approximated within a few percent by multiplying the skin depth by the outer circumference of the cross section. For typical 8 gauge cables ten feet the effective resistance changes from about 0.0064 Ohms to 0.011 Ohms. Put this in series with 4 Ohms such as a Magnepan speaker and the ratio of resistance is an increase on the order of about 0.01 db. Skin effect is not an issue and cable designers either know this or they ought to know the engineering/physics to calculate it. This issue destroys the credibility of so many of their other claims such as confusing grain boundaries with Johnson-Niquest thermal noise of any conductor and the insulation introducing electric field distortion from dipole molecules in the insulation.
I do not question the possibility of a badly constructed distorting the signal but I do not believe thousands of dollars or even hundreds of dollars for a cable can pass a strictly conducted double-blind test over a well constructed cable. Could anybody whose ego is connected with spending $12,000 admit they hear no difference they don't imagine? I am not so sure.

@drbarney1 , you really should have thrown in dielectric diffraction and triboelectric effect in there for good measure?  ... I am laughing with you, not at you.  I probably shouldn't tell you I once read a "respected" audiophile claim you shouldn't use speaker wire much bigger than 10awg because the effects of skin resistance get too large? ... ya, shook my head at that one too. Surface area is obviously too complex a concept for some people.

Barney, I think you’ve got it backwards, people buy expensive stuff,  because they hear a difference. Not buy it then feel like they have to say it’s good, though even then, I wouldn’t do that, as I do buy some thing without the ability to hear it first. Why is it that people believe that someone who purchases an expensive cable will lie about it, and yet not say the same thing about say an amp, or certainly not to the same level as with cables. It seems to me that some are trying too hard to convince themselves of something, so that their own ideas aren’t shattered. Hey, if you honestly tell me that you can’t hear a difference, where I honestly can, I’m not going to argue that at all. And I certainly would. It recommend that you spend money in that case as there is no value for you. Just as I might like electrostatic speakers and you might hate them. Then, why would I suggest that you buy them? Or just the opposite, why should I not buy something, because you don’t like them, or can’t hear a difference. Why can’t we each hear what we hear, and like what we like. No need to revert to arguments about how you feel some manufacturers market their products that you don’t like, we are discussing what I hear and like and what you like and hear, or don’t hear as the case may be. Why do so many feel the need to tell people who spend on cables that they’re basically fools and idiots, and have duped themselves into believing something that is not true. I don’t see those people trying so hard to convince the ones who can’t hear any differences that their hearing is somehow inadequate. 

$12,000 cables is conspicuous consumption especially when the laws of diminishing returns, if not gravity itself combined with the placebo effect kick in, and therefore immoral imho. 

Use lamp wire and feed the starving children in Bangladesh. 

No, they don't try to convince them of it. They just state is as a fact ... while never putting their own ears/brain to critical evaluation.

I don’t see those people trying so hard to convince the ones who can’t hear any differences that their hearing is somehow inadequate.