No one can, it is a catch phrase.
What I did was got my daughter to change cables whilst I did not look, so it was blind in that sense, not a catch phrase.
Having been well paid but busy until I retired my listening tests had been superficial or "long term" which I now know give bad results.
I had quite a few different cables, from adequate gauge wire off the reel bought from electrical suppliers, via normal budget speaker cable to expensive stuff from Goldmund and MIT.
When tested this way, with me not knowing which I was listening to and volume matched by not touching the volume control between tests, any difference I might have thought I could hear turned out not to exist.
Subsequently I haven't changed anything in my HiFi for 3 or 4 years yet I still think I hear "improvements" some days, which I would, in the old days, have put down to long term listening revealing the improvement of a new item. But there haven't been any, so it can't have been.
I subsequently learned our aural memory is too unreliable and short to make a trustworthy comparison apart from in the short term, which explains the error I had been making for decades.