What’s your vote for the most ridiculous, overpriced, and useless tweak?

Any and all cables that cost more than a couple of bucks.

That’s why they invented Bluetooth Audio for cheapskates 😉

>>>>>> I suppose you tried this outlet cover and found to be completely useless.....do you have any measurements to substantiate your vote? What receptacle did you pair this cover with? <<<<<<

I laughed when I read this.  Given the so-called high end audio business seldom uses specs at all, especially with these types of products, what specification would show what effect that a power chord, plate cover, green ink etc etc has on sound?

That is the magic dust that some people selling products depend on.  I/we have no way to experience or validate, beyond possibly double blind test, which the hard core disdain) if or what differences you/we say we hear.

 I am not denigrating ANYONE's experiences but do think some are self fulfilling prophesies and bias.  How a very very slight diminishment in some vibration can change specific timbre, sound staging etc in electronic devices..lets just say I am skeptical but kudos to Navy and USAF because their stuff seems to work fine on ships and aircraft  lol

“Given the so-called high end audio business seldom uses specs at all, especially with these types of products, what specification would show what effect that a power chord, plate cover, green ink etc etc has on sound?”

If you’ve tried any of the stuff you say, you would know the possible effects or no effects at all on the sound. Cause you will be speaking from your experience...otherwise you have no credibility (just like the OP) to diss a product that may be effective or completely useless.

In 20 years of trying many tweaks I know better not to deem a product ‘useless’ in a public forum until I’ve tried in my system.

I left out the great Immanuel Velikovsky  in my last post. Legendary, wonderfully entertaining read. Like a lot of the ads for cables and fuses and tweaks I see, great stuff and deeply amusing.

You just have to realize that you're in the fiction section. If you forget that and take the wrong things as reality, you may get people laughing at you.