How can I tell if my actual household is corrupted?

First, have you tested with no mods/CC at all? Drag the Mods folder to the desktop and rename it, delete the file called localthumbcache, open the game to test, and exit without saving.

Re. spreading, it's lot corruption, not household corruption, that spreads. 

To test if it's the household (the Sims) specifically, save them in CAS to your library. Exit, drag the Mods folder to the desktop and rename it, delete the file called localthumbcache, then start a new save and add the household from your library.