Favourite aunts, uncles or even parents, are seen - usually they have come to 'comfort' those they leave behind. It is assumed, even by Believers, that this 'proves' that ghosts are spirits of dead people and that most of them mean no harm. This is a great error, for all ghosts, without exception, are demons - wicked angels, followers of Satan whose only task on this earth is to deceive and to harm. We are told this in scripture. We are also told that no man has ever returned from the dead, except for Jesus Christ and those He raised from the dead as special miracles.
Ghosts are never friendly.
They are always wicked, even if they appear to be kind. Their purpose is to make us believe they are spirits of the dead. Once they manage to delude us, they continue to hold our attention, so that any belief we may have in God as He is presented in scripture , is eroded to nothing. Satan was the chief of all angels, of incredible beauty and power. But he sinned, even before Man sinned.