I have noticed that in my adsense account i am making money. But its not from my sites i have setup a channel for. Every site I ever made I set a channel for. Some of the sites i sold i am still earning from because they never took my ads off.(idiots) well anyway I am showing earnings from outside of my channels. And i have no clue where it is coming from. Like i said all sites i ever put adsense on i have a channel for it. any ideas on where its coming from? or how to find out?
You should have removed the adsense on the sites that you sold as if the other owners ever put anything up that is risky you may lose your adsense account because of this, contact them if you can still and get it removed. Regarding your unknown revenue generation im not sure. Maybe someone has picked up some content, plus the adsense code and placed it on another website.