I went on a ghost tour in Edinburgh, and we went through some old sewers/caverns under the city where poor people used to congregate. They told us that there was a ghost that sometimes could be seen walking around at the end of a long hallway - so you look down this hallway and just in the distance you could make out a shadowy figure walking back and forth... some people were really creeped out.
The tour didn't take us down the hallway, but I made a slight detour on our way out, and it was just a thick, black line painted on the wall at the end - it shimmered in the dim light when you looked at it from a distance.
After the tour people where talking about how they were now convinced that ghosts existed. I fucking hated those people.