I've added logic to produce a log entry for any sim who has a Sim Description (SDSC) but no User file, excluding known NPCs. The Sim Description contains a SimID which uniquely identifies a sim. The SimID is used to identify the sim by matching the Object Data (OBJD) GUID in either the User file or the objects.package (NPC).

The following sims are added to the game by EA, but they have no User file and there's no indication of their function in the objects.package, which means that they may just be garbage.

The questions are: Should I warn users about the presence of these sims? If so, then should I (eventually) "fix" these sims by removing their SDSC and all references? Note that I will not consider removing these sims until I can be sure of removing all references, including memories, wants, etc.

Since they are added by EA, I'm considering having the HoodChecker "recognize" them (ie, avoid giving an error if it encounters them). I have played a game with sims who have relationships with some of these "stealth NPCs" and nothing shows up in the game, so it's impossible to identify them. This is not surprising, since the majority of data about a sim is stored in the OBJD or other corresponding records in the User file or objects.package.

If anyone knows the purpose of these sims, I'd appreciate a comment.

The following SimID appears with no User files in all of the Pets, Bon Voyage, FreeTime, and Apartment Life stealth subhoods:
0x71B85E0D

The following SimIDs appear with no User files in the Seasons stealth subhood:
0x7040237A
0xF036D5C3
0xF03AE97B

The following SimIDs appear with no User files in the Bon Voyage stealth subhood:
0x73B38D46
0xF3B3896A

The following SimIDs appear with no User files in the Apartment Life stealth subhood:
0x01200000
0x01210000
0x01220000
0x01230000
0x158A6B8A
0x158A6BDD
0x158A6C30
0x558A6A92
0xF58A6C87

The following SimID appears with no User files in the Apartment Life neighborhood: Belladonna Cove. This is the only shipped neighborhood that I could find which has an stealth sim:
0x759390DF