LA Times – They came to the Las Vegas mansion in waves, chasing tales of ghosts and murder. Some came to gawk or snap photos in front of its black metal gate. Others came to worship Satan. Thrill seekers broke in and drew pentagrams and carved upside-down crosses throughout the house. The vandals came after “Ghost Adventures” featured the mansion on an episode that warned of a “nasty, evil spirit” that lurked inside. The homeowner fumed and sued. He wanted the Travel Channel show to pay damages. But how do you calculate the effect that demons have on property value?…