Their performance is based on the following:
1.) Physical build stress handling capability, ever wonder why cheap cables introduce noise when they are twisted and turned?
Mainly because the fibers inside them are constantly coming in and out of contact which changes the inductive reactantance in them to make the cable suddenly shift its characteristics and introduce noise due to the change. Good cables do not have this problem as they are more sturdy and have the outer coating to be more flexible and not allow fibers to connect or disconnect.
2.) Electrical Charicterisitcs
Every wire in the whole world, be it $2,000,000$ or $2.00, will generate standing waves around it, how the wire allows these waves to interact makes a cable good or bad.
Let's take a look at this:
sorry for my poor artistic skills but hope you get the idea
The extra mesh (or shield) which carries ground doesn't allow the standing waves to interact with the signal and thus helps in removing noise induced OUTSIDE the cable.
3.) Twisting cables in a way that they cancel out each other's standing waves also removes any noise which the cable induces to itself. This is also use in active noise cancellation, the principle involved is the superposition principle.
if we add the two waves they cancel each other out thus similarly if we turn cables in such a way that we can cancel their standing waves.
MOST important, in the cable all standing waves will try to induce themselves to remove the voltage difference between the cable and them thorough an open connector. In RCA cables this is prevented by the ground terminal to "guard" the inner signal terminal so that the waves don't interfere.
Other than this, to my knowledge there are no "quantum voodoo" effects which make cable costs go upward due to their "supreme" capabilities.
P.S. the reason why cable manufactures don't measure their cables performance using an FFT or an O'scope is due the fact that the magnitude of these waves is so small they "almost" make no difference once all of the above points have been considered.
Other than this, we have snake oil