They NEED TO BE TRAINED!!! If you dont build the muscle just like any other muscle they will look weak! Low body fat will show them, but if you dont train them they will look nothing like they could look. You think Stallone built his mid section on the kitchen alone, train you abbs and low body fat... it takes both! I started doing abbs 2-3 times a week from once a week and I can see a difference at basicly the same body fat.
My brother thought like this, he got down to around 9-8% over the summer and had crap for abbs! He never does them and even at low body fat you can tell they just dont have that shape or hard look.