So will the game cull unplayed households even if they're moved into a house? I hope not :(
The only time I had a massive cull was when I went on vacation to Granite Falls and when I got back home, half of the homeless townies vanished- even the ones I had invited to go camping with :(
Luckily, I had saved the ones I had given a makeover to, and made them proper households with their own house in the next game.
I get the feeling that the intention behind townies is that they're throwaways. If you really like a townie, you'll move them into your household or find them a permanent home anways.
As for the ghost- since I haven't done any legacy plays, I haven't experienced ghost cullings. Although I could see it as older ghosts finally moving on. "Walk into the light, Bob Pancakes..."