In a decomp, the scene is usually not quite as spread out as in a violent death, but a decomposing body can be even more gruesome than a suicide. A body that has been deceased for days, weeks or months has gone through some changes. In decomposition, the body swells, insects move in, the organs digest themselves and the skin liquifies.
Most people are brought to their knees by that smell, which is partly a result of ammonia gas released during decomposition. The coroner removes the body before the clean-up starts, but usually leaves behind lots of liquefied body matter and odors as well as maggots that are carrying the person’s blood. In addition to cleaning up the mess, cleaners sometimes have to track down and kill (by burning) any maggots that scurry out of the body and try to hide, because they’re carrying germs and might be carrying viruses.
It’s not pretty, but most people will tell you that the sight of a decomposing body can’t compare to the smell.