What is the meaning behind these ghostly appearances?

You have to ask yourself why would anyone want to spend decades and or centuries schlepping around the same place? Is it a form of punishment? Could it be a denial of death? Would spirits live in another dimension that is connected to ours only on some kind of fringe so that beings glimpsing into the others' dimension would view it as surreal? To me, these are the real questions to ask people like psychics or the "Ghost Hunters".

Why ghost appear is one of the things which man may never know. There are thousands maybe even millions of theories on why ghost sometimes appear to us including: they want a friend; they want to scare you; it's your minds playing tricks etc. But I believe that they appear only to some people because only some people can see the wavelength that the radiation emitted from them, just like how small amounts of people can hear a really high pitched noise (e.g. dog whistle).