I still get an adsense impression every single day from a domain that nobody has owned for 3+ years! Always one impression, always around the same time of day, EVERY stinking day. No matter how hard you try to remove all traces of a page there is always a copy, somewhere.
- removed url via GWT
- contacted adsense, got no response
- contacted my host, no help at all
- traced the originating IP, 95% sure it's in Yahoo's range.
In the end I whitelisted my own sites in adsense and called it a day, there is no page under my control with that adsense unit on it and I obviously don't own the unregistered domain name that adsense says is sending it so... if you figure this out PLEASE come back and share details.