Coprophagia is the technical name for what you are describing in your dogs behavior. Dogs eat faeces, it is a common problem. In most canines it is actually a normal behavior.Clean up any droppings immediately that way there is no temptation laying around.
Well if you all ever wonder why i choose this online name this is one of the reasons why. After my dog Gracie and her lovely smells and habits. I know not a good reason...go figure??