I certainly believe in a spiritual reality. And while I strongly associate this with a subjective aspect of reality this doesn’t mean what it might mean to some people, that these are intangible things which are only to be found in our head. On the contrary, I insist that the spiritual is more real and substantial than the physical. The difference is that spiritual things simply are not part of the mathematical space-time relationships which make up the physical universe. And this means that we cannot expect interactions with the spiritual reality to follow well-defined predictable patterns because if they did then they WOULD be a part of those mathematical space-time relationships which science is so good at revealing. Thus there is plenty of room in my metaphysical outlook for spiritual entities such as God, angels, ghosts and demons.
However there is a rather big difficulty in that the window through which the spiritual can act on the physical is extremely limited, such that it can all be dismissed as coincidence and happenstance. While this may be more than enough for God to interact with the world, for more limited beings like ghosts of the deceased this doesn’t allow much of anything. Furthermore, a great diversity in how different people experience these things is another defining characteristic. This will likely rule out a majority of portrayals in stories and movies, as well as most claims by mediums. To be sure, scientific investigations of any of these things will find nothing at all, because science is all about ruling out everything but the consistent verifiable patterns.
Also, personally I have no experience with any of these things (except God), at least none that I haven’t simply dismissed as nothing of significance. So I have no real reason to believe in such things, except as a commitment to the principle that the limits of my personal experience doesn’t define the limits of reality itself. So in a sense, I classify experiences of ghosts, UFOs, and fairies as spiritual in a semi-dismissive way. That is, I do not deny the possibility of the reality the experiences of others but know the inherent diversity of such experiences mean they will likely never be real to me in my life. I have no reason for dismissal or condescension for those with such experiences, but also no reason to accept that they have anything to do with me.
Furthermore, I would warn against attributing too much causality to the nastier examples because the more responsibility you grant them the more power you give them. You really don’t want these things to be very real to you, after all. I have little doubt that the all of these experience can also be attributed to psychological causes, but for me that really is no more than looking at them from a different angle.