I had the same problem once. To cut a long story short, the problem was that a pink flamingo that sat in the hallway had been kicked by one of the teenagers and had fallen through the wall. Once I had found it and realized that no sim could pick it back up I had to go into build mode, sledgehammer the walls away, sledgehammer/delete the flamingo, then rebuild the walls.
It took me such a long time to find it though as the sims only got the 'bad smell' moodlet in the kitchen and not actually in the hallway
. I had deleted and rebuilt the kitchen about five times and replaced all the counters and appliances over and over again. I was totally determined not to lose my house though as I had spent a long time making it perfect for my family and their needs etc
Glad you got your problem sorted Janna.
