Well, this did not go in the direction I had intended, but I suppose I should not be surprised. I guess the take away for me is "We don’t know what we don’t know".
There is a simple way out of this. Usually the problem is sorting out how to make the measurement needed. I’m sure you’re aware of the idea of ’if you can’t hear it, you’re probably measuring the wrong thing’.
So if someone claims a particular cable plays bass better, which not do a pink noise test and distortion vs frequency between the two cables of such a comparison? Do it with a microphone so the system in question is part of the equation. After that you can try to sort out why there is a difference if one if present. In this way you can see if expectation bias is thing or not.
I had a customer do exactly this and he found that a certain capacitor did affect distortion at various frequencies, verifying what he was hearing.