Hidden factors in A-B comparisons.

One word,"Static" Static can bulid up in cables over time. Making music less warm One trouble shooting tactic that Direct TV tells you is to disconnect 75OHM cable and brush your thumb accross to reduce charge. Now if your system seems harsh and you go decide maybe its the cables. You go buy a really good set of copper ones and now the music is now all balanced again. Wonderful. You keep the cables and sell the others when all it was just static build up causing the difference!!!! Also in the mix when you unhooked the cables you inadvertantly cleaned the contact points a little. I unplug everything every couple of months to safegauard against this. Also before I change cables I turn off everything and if comparing I turn off and unplug for a couple of minutes and plug same cables back in This could have an effect if your system was on a long time and stabilized. This is arguable of course.
Back when I was in high school (early 1970's), Stereo Review and High Fidelity and I think even Consumer Reports would recommend twisting the cable plugs while plugged in to remove any built up oxidation. What you are saying sounds similar.

I spray cables with deoxit while connected or disconnected not only contact surface but isolation as well.
I use Kimber 8tc bulk cable (got some deal directly from Kimber on unused remaining bulk and using them with no termination the vintage way:-))
Same thing I do with interconnects XLR or RCA. After Deoxit treatment on isolation the outside view is also beautiful and shiny.
Experts like George Cardas say that the kinetic energy from moving cables around causes a build up of static electricity in the cable dialectics and that cables need time to settle after moving them for this static charge to dissipate.

Switching cables back and forth without giving them time to settle after moving them is also not the ideal way to compare cables. I think the best way is to compare cables is to listen to a variety of music on one set of cables over the course of a couple days and do the same again with your other set of cables.
Interesting situation on the static and settling in before comparison. And, since cable comparisons typically are rather difficult to make on a blind A-B basis I think I'd agree that multi-day listening allows one to slowly get a feel for the overall sound or changes. (I've got a huge pocketful of money for the blowhards who think they can guess direct A-B comparisons when truly BLIND.)

I used to think blind A-B was the only way but now I'm starting to realize that for extremely subtle differences between high end components you really need lots of time to hear everything and to be able to make long-term comparisons.