I do not think there is a connection between regular human spirits haunting a place and UFO-Aliens. In some cases, photos of UFO's may well be spirit orbs and not alien life forms. I Have you noticed that UFO researchers see Alien-UFO connection in hauntings because it have share some common elements. They see what they want to see and not what actually is present. It is like they are looking for the most complex answer when the answer is the simplest.
Ghosts are everywhere and they are people without physical bodies.
I do believe that some energy orbs may be non-earth life forms, but they do not haunt homes and building, but they observe the activities of those about them. Just as the first thought when hearing of a haunting or poltergeist is to immediately conduct an exorcism. Hollywood influence upon us. It is our mind set that directs us in the wrong direction when we hear of a haunting. The first thought is to destroy or remove, not to understand and to learn.