My wife is convinced we have a ghost. And I'm not willing to argue at this point. We've heard cabinets shut in the middle of the night. A pop can (empty) got knocked over and off the hearth near my chair. And, while watching a movie with the wife, the TV just changed channels. All by itself. The remote was sitting next to my chair and nothing was around it.
Issue a challenge to the ghosts. If they think they're so tough, you'll know right away.
Otherwise, they're just all talk and no walk... ignore them.