Witch of Endor (1 Samuel 28): the appearance of Samuel was an exception, possibly demonic; the medium herself was shocked it worked.

The Witch of Endor was shocked when Samuel actually appeared — suggesting she was normally scamming people and possibly working with demonic spirits. The appearance of Samuel (if genuine) was an exception to the rule, not the norm. This supports the view that true contact with the dead is not the usual explanation for apparent ghost phenomena.