When I moved to my current house I had the electrical service completely overhauled with new main panel, and discrete lines for my main stereo system, and hospital grade receptacles. I then did some testing with a couple of others present, using regular power cords, some borrowed 'high end' expensive cords and some that I had made up myself using heavier than normal cable.
The results were interesting and saved me a whack of money - my home made ones were judged the equal of the audiophile super expensive cables in blind listening tests. The high end cables went back and I have been happy with the home made ever since. Had I not arranged for three of us to listen, I might have fallen for the usual "they cost a lot so they must sound better" myth of the high end stuff. Not saying that can't sometimes be the case, just that high cost and a fancy brand name guarantees you nothing.
I think that many purchases of things like that are later justified by people who think that if they don't sound better then they - the buyers- are idiots and of course that could never be the case, so....they mentally qualify what they are hearing..