There are many films and books about evil ghosts and unclean spirits, but the common denominator is that living persons are defenseless against their wills, and can become possessed by them and even killed. This perception, though it may sell the story to an audience hungry for the supernatural, could not be further from the truth; at least for anyone who believes in and lives the power of love, light, and cleanliness of mind—in a word, for anyone who is a true follower of Jesus the Christ and depends wholly upon his shed Blood for life and transformation.
Unclean spirits were by Jesus and his disciples routinely cast out of those who had in some way become possessed by them. There was simply no contest, and the same goes for our own day.
What are unclean spirits? We can speculate, but Jesus is silent on the matter. They may be disembodied human spirits. They may be nonhuman earthly entities. They may not be from Earth at all. They may even be the very principalities and powers and rulers of the darkness and spiritual wickedness in high places mentioned in the epistles of the New Testament. But what we do know is that they are not figments of a disturbed imagination. They are as real as we are. Too many people from all walks and positions of life have seen them, felt them, been possessed by them.
So, what do we do about hauntings? We take authority over them after we have proven ourselves disciplined enough to defeat them. What does this take? Holiness, even as God is holy. Outside of that, good luck, because you will need it.
But, what about the good spirits people see and hear? These are certainly not evil, but as Sheol (Hell) is all around us, so is Heaven.