yes, I do believe. Once, my parents and I went to a historic downtown restaurant that used to be the home of a wealthy industrialist in the 1920's. It was called The Whitney, and they said it was haunted by the man (the industrialist). I didn't really believe in ghost at the time.
Well, I had to use the restroom, which was on the second floor. Also at that time there was a private party being held on the second floor. I went upstairs to the restroom, and when I was finished I decided to be nosey and look around a little in some of the upstairs rooms. I went to a room towards the back and peeked in and saw a man dressed in fancy evening clothes. Thinking it was someone from the private party I backed away and then took a quick look again just to see what the room looked like. Well, the man had disappeared. I mean, completely gone--and there was only the one exit from that room, and I only glanced away a couple of seconds. So, believe what you want, but I believe I saw the ghost of the industrialist.