I listened (a long time ago), didn't hear any difference (back then) and because of that, I now don't believe they make a difference.

Is that clearer?

Expectation bias applies to me just as much as everyone else, no denying that.
Being an electronics engineer for years probably makes me less likely to believe what manufacturers say and look for reasons why these should make a difference.

I'm not questioning that you hear a difference, just why or how you do.

Some cables do make a difference, but this is a measurable characteristic and in the case of power cables, if there is a difference it means either the cable or the equipment isn't fit for purpose. Oscilloscopes don't have any bias.

It wouldn't be so bad if it was just a case of DIY experimenting and fun in a hobby, but the likes of RA selling �3.5K 1m power cables just takes the piss.

You seem to be getting quite worked up by this?
If you are happy with the results, however they get into the brain, real or imagined, then just sit back and enjoy them.