How to do deal with looters.

Bluebeard45

So instead of cutting off contact with other Sims they built a "welcome" area attached to the main house. The doors to the main house are locked and there is no furniture not even a toilet in the "Welcome" area. It's not pretty but my Sims keep there stuff.

crocobaura

Same here. I build them a somewhat large porch and they meet their visitors there. I tell them to "Invite in" but keep the door locked, so the visitor stays around until I send them home.