I'm not sure if I truly believe in ghosts, I think 99% of "ghost experiences" are just abnormal perception, coincidental randomness and/or hallucinations. I think most ghost hunting shows are 99% bullshit.
However, I truly did live in a haunted house once, the only place where I've had true ghost experiences. When I lived in California I lived in this houses built in the 40's and the street address was 666 [xxxxx] Avenue (I kid you not...).
The basement had an overwhelming dark vibe to it, we used to smoke weed down there and everyone who came over always commented about this. Oppressive vibe, like a spirit did not want anyone in there. Over the years both me and my sister would have many odd experiences. Hearing our names being called, knocking sounds, objects moving, cabinets opening during the night, piles of paper being lifted off the table and falling to the floor.
One time while walking to the kitchen I saw a full bodied apparition of a young girl, pale with black hair, wearing a white dress that looked like it was from the 1950s. She was smiling, happy, and did not give off a scary vibe. She walked right through me then disappeared. That was crazy.
The most insane part is that all 3 of us, including my mother who does NOT believe ghosts are real or anything paranormal, would routinely see the same apparition in the back yard. We all saw the same exact thing. A brown mist in the shape of a man pacing around or looking into the windows from the back yard. One night sitting at my computer I saw this brown figure staring at me from the window, when I looked over it ducked below the window as if to hide from me. At first I thought there was actually a man in our back yard trying to break in, I grabbed a bat plus a flashlight and ran outside but there was nothing. Both my sister and my mother saw this brown figure out there on multiple occasions. That's the craziest thing that happened. Either it was a ghost or some sort of shared hallucination occurring on multiple occasions. I have no explanation.
I don't know. I was mostly sober around that time and it's also well before I ever experienced psychosis. I don't think they were hallucinations, but I can't rule that possibility out for sure.
I still don't necessarily believe ghosts are real, but I can't explain any of that.
I've never had any other ghost experiences ever in my life, other than in that houses. Creepy.