Here is a pretty good article:
Are ghosts real?
by Gary Bates
If an interdimensional (as in, it looks as if it suddenly emerged out of nowhere) entity suddenly appears at the foot of someone’s bed in the middle of the night and claims that it is from the Pleiades cluster, then on most occasions the person will believe that its claims are true.
Meaning Christian Geocentrics who don't believe there are planets around the Pleyades and that angels about those stars are busy adoring God with the physical stars as candles would also believe that stuff involving obviously planets around the Pleiades and a Heliocentric Solar System for more than one star?
Or meaning a demon would not waste his time on such a Christian with such a message?
There was a certain monk who was visited by a figure claiming to be the angel Gabriel. He answered "why would Gabriel come to me a sinner?" - and something went away with (as I recall the story) leaving a trace of sulphuric stench behind. (Too bad a certain seeker in Arabia had not access to the faith and testimony of that monk ... I am assuming he had not).
And inviting ghosts per Ouija board is inviting the demons to fool one. Too bad Tellinger started dabbling in channeling (which does not discredit his claim the cities in South Africa are pre-flood, and it is so sadly ironic that "Enki himself" telling him how the "Annunaki" approached earth and needed gold are so close to Satan and his demons falling from Heaven and so close to greed being demon worship).
On one occasion a medium was shocked by the real ghost appearing instead of the demons she was used to. That real ghost was the ghost of Samuel.
However, if a ghost appears unprovoked (i e through no apparent fault of any medium), and claims to have committed a mortal sin which one should avoid, or to have died in sin and got damned through an accident in a dangerous place, or to be in purgatory and in need of prayers, then there is a chance one should heed it. That is the conclusion of St Gregory the Great in his works Dialogues.*
Then there is the matter of "interdimensional." According to St Thomas Aquinas we would rather say that angelic beings relate to our three dimensions in a different way from bodies. Bodies are in space, but space is in spirit, but only a certain portion of it - when it comes to created spirits.** God obviously "surrounds" all of space. And Hell in the middle of the Earth and Heaven beyond all planets at least are parts of the physical world as well as being abodes of souls. There will be risen bodies there.
Father Brown was once asked why he did not believe a certain esoteric explanation. "It is my business to believe some things, and so not others" he replied.
BpI, Georges Pompidou
St Rose of Lima
*When saints appear, it is not like ghosts, and the Church usually is very reserved about the seers, till some discerning has been done. Same applies to Jesus and Mary, Our Saviour and Our Lady.
As to the ghosts I have been singing of, if Molly Malone was Church of Ireland, no proper requiem mass was said for her. And the swagman with his waltzing matilda obviously reminded that suicide (even if provoked) leads to damnation.
*At a time.