The "most foolish" loudspeaker tweak/upgrade ... is

Long ago, I purchased a pair of speaker cables that dealer said were directional. He told me if I didn’t like the sound initially, he said to reverse the connections. Go figure.......

My dealer told me the same thing.
At first they made the music too bright, so I reversed them.
But that made the music too dark.
So I reversed only one. Then it was just right.

They were Goldilocks cables but I don’t think they are available anymore. Bummer.

I think the problem is that peoples' mental self influence is often stronger than their audio memory or discrimination.  I feel it myself most times I try out a new piece of audio gear that I've just purchased with the intent to upgrade. 

Actually, the poster above's comparison to fashion might be the best I've heard.  Fashion is totally subjective and in no way quantitative.  Of course fashion is fi kle and influenced by celebrities, price, ....   There is no objective measurement nor any pretense of one...  The audiophile world is very different on that account.

Because of Doug I've rewired my entire home.  And the lines into my home.  I'm trying to get comed to change theirs too.  Until then I can't listen to my system.   

I use a cat trampoline to suspend my cables inside the speakers

I use my grandpa's suspenders to suspend my disbelief.