No matter how much people try to say they've seen ghosts, it's been proven many times over and over that they are just illusions created in the mind. A hormone called 'septochlyriomide' (not sure about the spelling) starts spreading in your body if you are extremely sad, like example your relative/parent/good friend has died. There was a document on BBC "Dude, there's a ghost behind you" or something like that in 2002. The people didn't know they were being filmed and they had some electron panels in their foreheads and they thought they were seeing ghosts almost all the time even though the other people around him couldn't. Later on, it appeared that the images were just created in his mind. There were many occassions where he would say "yeah, the ghosts look like silver-colored, they always do", then the next day he would say "they were about as tall as me and green". It's just something that desperate people try to say to get attention, no offense. I could believe it maybe if it was a priest that has had mystically all of his brothers, sisters, parents and relatives die because of a mysterious disease.