In my experience, the only time I was contacted after being df'd was probably because my mom learned of my new address and asked the elders to contact me. This was prior to the internet being widely available, so I doubt they found me on their own, as my last name was different, I was in a state different than the one I was df'd from, and I'd moved several times.
They never bothered me again after the initial visit, because I told them that my current husband would more than likely use physical force against them. He really, really, really doesn't like jws.