I suspect that the speculators are scammers anyway: they never respond to my questions.
I still receive occasional postcards from real estate mogul wannabes for a property out in Colorado (I'm in PA). The previous owners of our house moved to Colorado after they sold us their house, and I assume their name is linked to our address in some gray-market/online DB. Why they wouldn't just send purchase offers direct to the house in CO instead of what they think is the owner's primary address (ours) I don't know, but I'm sure they fire off thousands of these things and don't really care how many are accurate.