clean-up. i have a poop eater, he started when he was around 4. he does it, as best i can determine, cuz he likes it. it's self rewarding. most of their "business" is on our walks and I always supervise in the yard and pick up immediately if they do go in the yard. yes in the winter as well. my yard is always clean!
ETA: he is now 11 and still as bad. it's the only thing he does when offleash it seems, search for and eat poop. it's obsessive even.