Enter the lot and 'unown' or remove any ownable vehicles, they can play up when the owner no longer exists. Remove any personal 'unbuyable' items like hobby plaques, holiday souvenirs etc., most don't cause problems but they shouldn't be left behind. I'd recommend using my CJH_LotCleaner.zip which deletes all controllers, NPC Schedules and any off-world items.

I have a backup of my main 'hood with all sims removed and every lot cleaned this way that I frequently use for testing and, after I unowned/replaced the ownable cars I have never had any other problems with it. Most of the lots had previously been occupied to three generations.