Liver failure happens when large parts of the liver become destroyed beyond repair and the liver can't function properly. The liver helps in the digestion of food, filters and eliminates certain toxic chemicals in the blood, and makes essential proteins among other functions. People with advanced liver failure have a yellow appearance because the bilirubin accumulates in the skin. It causes a decayed blood or mousy smell.
In Cirrhosis liver cells are destroyed and replaced by scar tissue (nodules) which hardens the liver and reduces blood flow and causes the death of even more cells. As a result an individual may get a breath odor described as decayed blood or rotten eggs.