There may be a way to prevent that by a mod I'm not familiar with, not sure. But the underlying issue is that inactive households, those not being controlled by the player, tend to go into semi-hibernation mode when they aren't being played, visited, or their lot isn't opened up and animated by the player. Thus the sims living there may have just enough simulation time to make a mess and break things, but not to clean up or repair them. So to us it looks like they may have been living under such horrible conditions throughout, but the sims don't even notice until they are animated again.
Once it happens though, NRaas MasterController (MC Cheats module required) has commands for Clean All and Repair All on the Household menu that can help make these visits more pleasant, at least to begin with. It's also possible, though less likely, that your sim's neighbors are all really just a bunch of Clumsy Slobs by their traits. Not to be judgmental or anything. :)
