The two blondes, who dated Playboy founder Hugh Hefner in the 2000s and starred in the reality TV series "Girls Next Door", recounted unexplained experiences living in the iconic 29-bedroom abode, which was built in 1927.
"You definitely felt the nostalgia and the old energy. I had little things happen," Bridget told Nylon magazine.
She even thought she knew one of the ghosts who appeared in her closet doorway one day, "She had long, black stringy hair - very pale, very thin. She was wearing a white T-shirt that was too big on her and black acid wash-y jeans. She was more modern-day, and I feel like I recognised who she was."
Marquadt believes it was the spirit of a woman named Joanie, who had helped the mansion's guests and looked after the pets before she died of cancer.
"There was a new pet in the house, and she was just seeing what was going on. I think it was a loving thing, but it's scary because it's shocking," she said.
Holly explained she was once in the basement gym when she saw a woman leave the bathroom and cross in front of her while moving towards a doorway, which contained a closet, meaning she would have had to pass by the star to get out.
Madison tried to "rationalise away" any supernatural activity, but one day was stunned when she was talking to Bridget and said she wanted a sign of supernatural activity - only for a TV to suddenly turn on.
"For me, it took a bunch of different experiences before I thought, 'OK, there's something weird going on here.' "
"I said, 'I wish I had more proof it was real,' and right away when I said that, her TV turned on by itself, and the volume went all the way up."