These devices actively listen. First gen LG OLED - Went over to buddy's house with a new one. As an experiment I spoke spanish in front of the TV and the next ad to play on YouTube was in spanish language. We're talking two english speakers in a household environment that would have zero use of spanish outside of what I did.

I visited a week later and he had reset the TV because he started getting spanish ads. On my way out the door that time, I randomly said something like "I can't hold it in anymore, I need diapers!" and my friend was like "dude don't do that."

Sure enough, not a day later... It really just Depends.