Signs of Corruption

"Springfairy556;c-16312126" wrote:
You look at your save file and the sim's photo is all messed up or their lot isn't showing.

Missing lot thumbnails in the save game chooser can also be due to tents being put in chests. That's not corruption, just a bug. Moving tents out of chests will restore the lot thumbnail in future saves.

To answer the OP's question: one thing that would suggest game corruption to me would be pets (or boats) on a sim's family tree.