I've had these ghost problems for a very long time. I started a legacy household where I made a family cemetery of the home lot. Definitely not a good idea.
3 generations down the line (and the founder fulfilled the "Surrounded by Family" LTW), I had 9 ghosts on the lot 24/7, in addition to the 5 flesh and blood sims who were supposed to be living there. Each sim kept a radio in their inventory so I could wake up the ghosts napping on the beds, so that the living who actually had jobs could get some sleep. Showers and sinks were constantly spraying water, and computers, tv's and stereos were constantly busted. And I got to the point to where I had to put a chair in front of the refrigerator to keep them from filling it to bursting with leftovers.
What finally ended that game was a single width staircase to the basement that went through the foundation. I had a living sim who was taking a shower in the basement workout room who had to leave for work. As he ascended the stairs to the landing, one of the spectral squatters started to go downstairs. They met on the landing and got stuck there. I reset him, and he went off to work, but the ghost continued to be stuck on the stairs, rendering the basement 100% inaccessible. This was before I knew that the reset sim cheat worked on ghosts, too...so I abandoned the game entirely.
This incident inspired me to do two things: I never place gravestones on a home lot, and I never build a house that contains single wide staircases.