I saw in the show your paranormal builds a really cool looking decor center piece link posted by CatloverPlayer he got from twitter. It had the seance table with the decor skeleton doll and it looked really cool. Looking at it I could see a lot of moo was used in building it. I liked it so I made a similar decor piece for the front yard in my build using moo. I used the seance table, the decor doll, flowers, and the grave lights. Put a fence around it to keep sims from using it and turned off moo after building it. I happened to click on the seance table while play testing the lot and my sim walked over the fence and used the table.
So I saved it as a room and using the world editor I placed it on the lot next door. I replaced the fence with half walls, moo is off, never turned it on to place the lot or half walls. I sent my sim over there, she walked over the half walls and used the table. The seance table has a large footprint and a sim can go over any surface to use it. The game is not designed to do that so I knew that it had the potential to really break the lot, trap a sim behind half walls, break the sim, or even corrupt the save.
So moo can cause problems that a quick test can miss catching, even if moo is turned off after using it to build something.
Also for finding missing ceilings under the roof, put the walls all the way down and you can see under the roof when you go up a floor level in build mode.
