Crime scenes can get extremely messy depending on what happened, and crime scene clean ups can be the most difficult thing one could ever have the job of doing. The odors that can linger behind, even after everything is cleaned up, can be devastating. This includes one of the main messes that occurs at a crime scene, blood, which will smell up a room in less than ten seconds. It's only natural that the smell of blood lingers for a long time after it's been spilled in a location, especially if it was on a carpeted area.