Why do dogs eat their own poop (coprophagia), and how do I train them out of it?

Quick answer

Dogs eat feces due to nutritional deficiency (indigestion), too little food, anxiety after being scolded for a potty accident (trying to 'destroy the evidence'), or simple curiosity/play. To fix it, redirect their attention with a treat the moment they finish going to the bathroom and reward them, while making sure to clean up waste quickly so it's out of sight — that environmental setup is the most important part.