EDIT: Never mind, it didn't work on my test save, I just now tired.
Try doing this. Take one single wall piece out of every room to make it one big room. Save the lot to your library and save your sims to your library. Delete your save, quit, and start a new game. Rent the same apartment, bulldoze the lot and put the lot you saved there. Check the traits, they should be empty. Then you can replace the single wall pieces if it worked.
I had moved from the tlc lot to the gremlin lot on culpepper. I didn't mind fixing the broken power box and the pipes, but I was tired of the bugs, mice, and smell. I did what I told you to try above, on the gremlin lot and when I checked the traits they were empty.
