You would love my next door neighbors. They moved in the same week we did 2 years ago. We saw them when they first drove up and enters their garage (middle age couple). Since then, nobody has ever seen them. They never have lights on in their house at night. They never answer their door. They never open their garage and drive away. They never have packages or anything else delivered. They only way we know they are still alive is their trash bins go out and are taken back in every week (though nobody has ever seen them do it) and in the winter you can see the white smoke/condensation from their utility vents.