Sometimes when poop smells really bad as in smells worse than normal it can be caused by foods you eat.
Other times foul smelling poop could mean a serious health condition with your colon or intestines due to bacteria buildup inside your colon and intestines.
Really foul smelling poop can also be a sign of a serious condition known as Celiac disease.
So if your poop continues to smell foul then you should see a doctor and get tested for Celiac disease or other conditions.
Poop should not smell really foul as in more foul smelling than normal.