I see the ads on Facebook quite often. I have not looked at price because I think it is snake oil just like the ones that claim to increase MPGs. It is something that you can just plug in the closest outlet to the panel box. That right there should put people on high alert. Lots of comments about how great these things are. I think all the comments are generated by the scammers. Anyone actually fall for one these ads? Some state they are some kind of capacitors that clean up the electricity. When I worked in plant management at a large tile manufacturer I know we used some electrical devices that were suppose to clean the electricity but it was all about protecting expensive large machinery.

It's snake oil. Trying to take advantage of gullible people.

Yep, just like the $49 robotic pool vacuums that sell everywhere else for almost $200. I just bought some algaecide on line now I see the ads every time I open FB. FB is scammer heaven.

Just read the 30% of reviews on social media are bogus and advertisers actually suppress negative reviews and comments. I would say in this case the numbers are much higher. I looked through a lot of comments and saw nothing but positive reviews.

I haven't seen the ads. Are they talking about something for home use to correct for power factor loss? I wouldn't think the average house would have enough inductance to require power factor correction.

Well...it used to be just induction motors. Now we have Switching power supplies, which can introduce harmonics:

Modern switched mode power adapters and chargers (just about everything these days
Some TVs
Newer computer power supplies
Variable frequency and pulse width modulated drives, such as variable speed blower motors and high efficiency variable speed compressors.
Newer microwaves
Induction cooktops
The charger part of your UPS\Battery Backup units
Both florescent and LED lighting

I have no idea how much this totals up to in the average home and how it impacts your electric meter, but harmonics in the home are a thing.

I thought about this too. I would think motors would be the biggest problem, and most already have a capacitor for phase correction. And there just aren't that many motors in a house. And then wouldn't phase correction need to be done at the source? Not at a plug somewhere in the house?
I suppose I need to read up on these gadgets

My thought exactly. How can a device plug into a little used outlet that is on 1 circuit result in any savings. The closest outlet to my panel is a sprinkler outlet in my garage. For the most part only used for charging boat batteries and a leaf blower.