Friendly apparitions don't seem to deter people looking for a home.Sites of murders or suicides are another story.
Infamous deaths can make houses especially hard to sell. Think of Nicole Brown Simpson's townhouse or the house where 39 members of Heaven's Gate killed themselves to join a spaceship presumably hiding behind the Comet Hale-Bopp or the house where Charles Manson's followers killed actress Sharon Tate and four other people.