Great thread!
I, like the OP. has been annoyed by these truths too much repeated that customers are most of the times deceived by their hopes,marketing ploys, and biases and placebos...It is true to say that but audio is a learning road...And most products are good to try if we want to travel the road...No denigrating is needed...
For sure i experienced this truth with ALL products i bought to upgrade my system to some degree especially in the beginning when I was unsatified ...No upgrades in spite of their improvement were working enough though...
The reason is simple:
i was not mature enough in audio to know how to work on the essentials key factors in audio: embedding controls and especially acoustic...
Acoustic experiments are listenings experiments...They dont always lie, and even when they lied you will be able to discern and master the truth which lay behind or in front of the acoustic "lie" anyway ...
We can control acoustic almost "at will" mechanically with Helmhotz method and with passive treatment... Mastering "illusions" from our brain is part of the acoustic experience not his foe....
I dont like to be accused of being conned by myself or conning others using cheap "herkimer diamonds" or S.G. or ionizers for example with my main mechanical acoustical device....
Most people think audio is a string of purchases...
I think audio is a string of experiments...Be them a new purchase or not....