What is the Silliest Accessory You Have Ever Seen.

If someone buys a product and they hear what it claims to do, then it works.

That doesn't mean it's exempt from being goofed on, because of the ridiculous marketing and odd appearance.

I like to believe most of us just want a stereo=source, amps and speakers without any nonsense between all of it to sound convincing.

Add to that a room for those boxes to sound their best.

How about painting the outside of your CDs green ??
Some here may know about that  ( many years ago ) some may not .
I tried it---A waste of time . I want to say , without being critical , I have tried and do believe in some tweak ideas .
Generally , I try to take a consensus, by getting with friends or digging on the audiophile net for ideas and research . That is part of what this hobby ( that I love ) is all about .

The silliest assessorie that comes to my mind is the LP spindle hole enlarged. What, doesn't anybody own a pocket knife anymore? Enjoy the music

I heard PWB demos back in the 80s. They work. Except, they don't. Your brain processes inputs with more quality the second time. Try reading a page from a book you've never read. Twice. So the con is to play music without the tweak and then with the tweak. After that, it's psychological. 

Some guy makes a parabolic-style reflector from thin laths of wood. It sits behind the speakers. It works much like cupping your ears. Not bad until you hear the price. $30,000+.