Are earth-bound spirits real? Can they affect us in any way?

Aside from the Halloween obsession with ghosts, we want to look at the possible reality of spirits who have not yet made the transition to the higher planes. They are often stuck in their plane of reality, not even realizing that they are no longer in body. Maybe their time of transition was traumatic, such as in sudden death, suicide or even homicide. Are they evil? Not necessarily. But they may attach themselves to us in order to have access to our life force energy. They can become psychic 'vampires', seeking to control in order to feel validation and importance.