Why do dogs eat poop or feces?

The leading cause is boredom, especially in the case of playful breeds. These dogs dislike idleness and if you do not occupy them, they will find something to chew up. Grass could be the only abundant thing they can find. Grass eating is not a harmful habit unless your lawn is fertilized or sprayed with chemicals. 

Hence why do dogs eat poop.  To learn more, visit this website about why do dogs eat their own feces.