In the 70's and 80's, I remember people coming in via door-to-door.In my life, I had two Bible studies with people I met door-to-door, but they didn't come in. Over the years, I often thought it was my fault for not having studies and for them not coming into "the truth'. But it was a common struggle for all JWs.
Today, in this Internet age, I believe it is very, very rare.
But it does happen sometimes. A tragedy, moving to a new area, a life change leaves people open. Then some friendly people come by and gives them attention. Perhaps they are predisposed to learning something about the Bible and the JW message seems to make sense. They fail to google.