Who Tried Power Conditioners Over The Years and No Longer Use Them Today, Any Why?

I believe every home is different power wise and I honestly don't think I would benefit from power conditioning. My house of stereo is on a completely separate power feed from the main house and I experience zero hum, no background noise or interference of any kind. My system in there has always had the blackest background no matter what I ran. And even with stock power cables. I replaced them all with Patrick Cullen Gold series cables just to see if there would be any improvement and there was none. Now cable connects, that's a different story. Upgrading my RCA cables had a profound impact, specially on my digital gear. I do live in a small remote community with all underground utilities and that may be benefitting the quality of my power vs folks who live in big cities, specially in apartments. Plus building the house of stereo from scratch with a very capable electrician obviously paid off. BUT it turned out more expensive than a top of the line power conditioner 
🙂

If you are connected to the grid in anyway you need a pure sine wave AC conditioner.

Even if you you are off grid, it's highly likely you still need one.

I've been using power conditioners since my 1st Adcom ACE515 Enhancer in the early 90's and today using a Furman Elite 15PF with Monster AVS2000 stabilizer. I will never get rid of my conditioners, to important in my system and also in my opinion. 

" But profits come from satisfying consumer demand."

No Miller.  Profits come from stimulating it.

You've said it Miller:   "Selective memory nostalgia", is when you think you hear a difference after adding a passive component that you've paid a lot of money for, and then it gets locked in by the warm feeling generated by the apparently positive response to your wise spending.  We all have the urge to feel happy whether or not there is anything to be happy about.

As far as passive power cords are concerned, all will do the same job as long as they can pass all the current demanded without high resistance.

Power conditioners can be useful if they can actively remove noise and other unwanted artifacts from the line.

Interestingly,

Plugging my amp directly to the outlet (instead of three different high quality multiplugs I’d sampled) made my system more dynamic, rich, and full-sounding. It wasn’t a figment of my aural imagination…it was clear, evident, and palpable. I gave it time between configurations, and ended right back to just plugging straight in. 
Then, I replaced the cheapo outlet with a Hubbell oulet, and there was an additional improvement (although that might have attributed simply to the fixture holding the plug more firmly/increased contact). 
I still use a Furman multi for the rest of my components, for convenience.