There is no such a thing as a ghost.

There is no such a thing as a ghost.
Ghosts are demons. People always say "but that spirit helped me to find something" or things like that. However, they do not understad the evil agenda: to drive alway people from God, period. Anything that it takes: to make you rich, to heal you (often from a disease the demon himself caused), ANYTHING that it takes. A life time of happyness is a small price to pay for a demon if it helps.
The bible says:
Hebrews 9:27
27.
And inasmuch as it is appointed for men to die once and after this comes judgment,

So, whatever drives you away from Jesus Christ and God is good for a demon, that is why the spirits can look like they have no interest in harming anyone, all the demon needs to do is to decieve, if what it takes is to "haunt" a house for 300 years, that is what he will do.