All I can add to this is my own personal experience. Some will believe me, some won't.
Let me start off by saying that I do not believe in spirits, ghosts, demons, etc., in their traditional applications. I had always thought that people's claims of seeing ghosts, being demon-possessed, clairvoyance, psychic abilities, etc., were nothing more than delusional hogwash. I still feel this way, more or less.
About two years ago, I took the job as head manager/ bar manager/ hotel manager for a rock & roll bar/pub with an 11-room hotel upstairs. This building was built in 1904 along the Willamette River in Portland, Oregon. It has Oregon's oldest liquor license and has been operating as a bar/restaurant since it's opening. During prohibition, there was reportedly a speakeasy/opium den in the basement. The building has countless claims and press as being "one of the most haunted places in the Pacific Northwest". There were accounts of there being a brothel in the upstairs portion which is now the hotel in which one confirmed murder of a prostitute took place. There are also accounts of people dying from consumption in the hotel as well. When the person who's job I was taking over left, he told me "good luck and I hope you don't scare easily". I didn't think much of it as I didn't really believe in ghosts or hauntings. The events that took place shortly thereafter changed my view on hauntings forever.
My desk was in the basement. Mind you, the basement of a 100+ year-old building is naturally a bit creepy. The lighting was sparse, it was musty, cold, etc. There was a particular corner of the basement that just didn't "feel" right. It was always darker and colder than other areas of the basement. There was a light fixture in that corner in which lightbulbs would never stay screwed in. they would loosen so that they would flicker endlessly. There were many times that I would go to tighten the lightbulb in the socket, only to return mere minutes later to find it flickering and loosened again.
The weirdest phenomena was that when I would run upstairs to grab an invoice or something from the bar, I would be gone from my desk maybe 1-2 minutes, tops. Many times, I would go back downstairs to find that my desk chair had rolled 30 feet from my desk, around a corner, and uphill where I would find it spinning in the same corner as the flickering lightbulb. This happened at least a dozen times. I'm not trying to say that it was a "ghost", but SOMETHING was making my chair move across the basement. There were no other people in the basement at the time of these incidents, either. I did not do drugs or drink while on the job, ever.
I would also hear disembodied coughs that sounded as if they were 4-5 feet away, but I would be completely alone. I would hear whispers, screams, groans, etc. Once, I felt a hand on the back of my neck, but nobody was around but me.
It finally got to the point where I would be afraid to go to work. It was very uncomfortable to be there. Many times I would be there completeley alone before the other employees began to trickle in. Those times were the worst, because I eventually began to come to terms with the fact that I definitely was not alone in the building. The other employees all had their own stories and experiences too. One of my cooks was struck in the side of the head by a flying jar of mustard TWICE in one evening, enough to make some pretty impressive goose eggs and bruises. Guests of the hotel were constantly complaining of strange disturbances during their stays as well. We had a hotel "ghost log" behind the bar where guests and employees alike would write down their experiences. It was many, many pages long.
I finally asked to be transferred to a different property within the company because I grew tired of being scared and uneasy all the time at work.
Like I said, I still don't believe in ghosts, demons, etc., but what I DO believe is there is some sort of strange, unexplained phenomena causing very mysterious things to happen at the White Eagle Saloon & Rock & Roll Hotel in Portland, Oregon.
Many of you will not believe what I've written here, and that's ok. It does sound a little far-fetched. All I can say is that I witnessed this stuff first hand and it affected my life in a very negative way. I can't say that I know what caused it, but I can definitley say that it was something beyond my ability to explain or understand what was causing it.