Most likely you have heard tales of the Halloween haunted attractions that are really haunted. I am sure that many of these stories are sales hype, but one local haunted attraction actually had so many problems that they brought in some paranormal investigators.
The investigation took place during the off hours, and not only were they able to capture EVP, and images on camera, but one of the investigators was physically attacked, and became so ill he had to leave the building.
I have heard of several of these haunted attractions that were actually haunted; one reason could be that many of them are operated out of very old buildings, but another reason could be that the ghosts are attracted to the energy that is in these locations. Night after night hundreds of people are scared witless, which leaves behind a lot of energy that negative spirits may feed off of.
It is something you may want to think about when you are walking through a haunted attraction next Halloween. That ghostly apparition that you glimpse down the hall may not be special effects.