Yup I've seen alot. I once mastering martial art and can sense "Jin" (Arabic name for spirit/demon/ ) they had several gate on our world. They dont require any human technology to come but indeed require human coorporation to interact (exorcism , paranormal activity). They dont look like what in picture, in our dimension, and can shape what ever they want, what you see a ghost actually just a "Jin" imitate the people who is already dead. They just a normal creature, some of them are Muslim, Cristian and Jews, pagan, and Lucifer worshiper even some are atheist. They can produce like human (although not the same characteristic ). It's look like nonsense but if you come to my country a lot of people is still able to do this. They are live among us in bad, celling, on roof, in toilet and they can see us but only small of people who can sense their existent.
True. Those are demons, and there are not really ghosts anywhere, just classes of demons. Those that imitates the dead are the familiars. They follow us around everywhere and can imitate members of the family...
The thing is, they need a footholld, a legal right to do something: could be that you praticed sorcery, had homosexual relations, used a drug, was rapped... There are many ways they use to have a foothold into a person.
They are all around but they only can interact with the tainted.
Actually the "only special people can see them" is part of the lies to make people want them in their life. It is all about pride with the humans, Satan knew that. His first lie was: eat this and you can be as gods, you can be so special...
And the demons use the same lie till this day. But make no mistake, this has nothing to do with being special or diferent, it has everything to do of how much legal right you give to them. And it may cost your soul.
As always, no vitamin C or salt water will work, the ony medicine is Jesus Christ.