A 'dirty edit', is when a DLC (or a mod) contains data which removes an object by deleting it. Why Bethesda didn't think it was necessary to spend the 10 minutes it takes to clean up their sloppy editing before release is a mystery, but fortunately it's very easy to clean it up for them. However, when mods are loaded, these dirty edits can cause crashes. These 'dirty edits' are not causing any problem if the game is left un-modded. Info: Bethesda's official DLCs contain deleted references, which can cause problems when modding the game.
