For example, my sister in laws' partner is 62, R.A.F. retired after 27 years service, and a solid sort of guy.
However, he was brought up by his grandmother who was a "dabbler", as was his first wife.
About ten years ago, he and the sister in law had two friends round for a meal and a drink, (not too much drink as they were driving), and the subject turned to "dabbling" and my sister in law said something regarding her dead grandmother.
He doesn't recall what happened next, thought he dozed off for a few minutes.
She said that as they were talking, her partner took on the appearance of her grandmother. One second he is sittiing there, the next there is an old woman sitting there. The two guests saw it and gasped with shock, and just as quickly, things returned to normal. The guests got up quickly and left, and never returned.
That is a true story.
Sister in law didn't meet her partner until after her grandmother had died, and he had never seen a photograph of her. This apparition wasn't just any old woman, it was in every detail, the grandmother.
My sister in law had herself visited spiritualists a few times over the years, something I warned her against. She doesn't now, or at least, not to my knowledge.
I believe that people who search, invite something influential into their lives, and if it's not the Holy Spirit, then it's a demonic influence.