This can also be caused by:
1. Fires. Like meteors, fires will char surrounding objects. It could even be a small object like the vase with the daisy in it. You might not notice it because it doesn't look charred.
2. Sometimes dirty dishes can get hidden in hard to reach spots if you dragged and dropped the dish to the trash, but didn't notice that the dish never actually made it to the trash. For example, it can get stuck beneath stairs and you might not see it. Sims won't be able to get to it to pick it up, either.
3. If you're using cmo's cat perch from ModTheSims, the sims will sometimes set a dirty dish on the perch and then the dish becomes invisible. The invisible dish will go bad and cause up a stink but you won't know it's there.