The idea was that different households picked different devices/services/companies and fed each with a random but plausible keywords to see if this is actually

The idea was that different households picked different devices/services/companies and fed each with a random but plausible keywords to see if this is actually covertly picked up and ends up coming back to us on some other channel later on. I had an Echo that I installed in a spare room in the house and used for a short time exclusively to have these made up conversations next to it and keep talking about a "Whirlpool washing machine" without ever using the Alexa hot-word. The keyword really couldn't leave that room except via the Echo. After a short time to my surprise I started seeing this in my Amazon. I have no doubt that the Echo is (at least occasionally) listening and sending information without any indication that it does. My friends tested their own stuff in their household with their own keywords in much the same way that I did. Google Home, Apple Homepod/Siri, Facebook, Microsoft Cortana. The only 2 people who saw their keyword pop up again were myself with Amazon and one other with Facebook. I can't draw the conclusion that Google does not do this, maybe they just do it smarter. But I can certainly say I cannot under any circumstances give Amazon the benefit of the doubt.