Do I believe in paranormal activity, spiritual forces, and hauntings. Yes. Do I believe in spirits of the departed lingering. No. my personal belief is one of the activity of angels an demons, and either could take the appearance of a person to achieve an end. The end could be to comfort and aid, or to decieve, frighten, dismay, etc.
To me spirtual forces are very real.
However, that being said I also believe that people have a tendency to see what they want to see. If you are seeking an encounter, I'd say you will find it.
I recently saw pictures taken by a personal friend of mine. These were not high budget shots, but prints from a 35 mm. camera fresh out of the developers envelope. He was visiting the south and took pictures in a cemetary. In the developed pictures there were greusome faces in the trees and bushes, that woud be the kind I would expect a demon to look like. Pretty chilling to see.