One particularly religious friend told me he believed that ghosts were the signs of demonic possession. A person, while alive, became possessed by a demon, and when that person died, the demon remained to haunt the house. So, if your grandpa haunts a house you now live in, that's a sign that your relative was possessed by a demon while he was alive, and his soul was destroyed. And that demon is now sitting around, waiting to possess you too. I can see why he'd think my stories were creepy.
What do you think? Would you read a book about ghosts, or do they give you such a high level of heebie-jeebies that you couldn't stand to hear a ghost story at a campfire before you go to bed? Are they just bunk to you? Stupid? Too frightening? Too sinister? What do you think they are? Would you be tempted to read it? Tempted to burn it? Tempted to read and then burn it?