Exactly. I may be wrong, but by "snake oil" I do not refer to some actual higher audio quality only interesting to/perceivable by some. that is actual quality, that is real.

I refer to non-existing higher quality that some clueless people believe in. There are speakers that cost tens of thousands of dollars that produce sound in any way measurably better then other speakers that cost on the hundreds, neither by using instrumentation, not by testing them by blindfolded expert listeners. Same happened with Monster cables, or "DAC with optic readers", as Audiphiles would call them (CD players).

I think I mentioned of an audiophile who claimed white walls would be best for listening to music, as they do not "emit" (what?!), while walls of any color (as if white is not one) do "emit" and therefore interfere with sound waves. Yes, if you're thinking in light terms, he even got it the other way round.

Or, I remember several threads here about digital cables supposedly producing "better sound".

These are all cases of snake oil: there's just nothing true to them.