From everything I've read and heard, some dogs do it and some don't. I don't think there's really a logical reason for it, and other things I've read tell me that pineapple and other additives don't work - just pick it up ASAP so it's not there to snack on! I've only had one poo eater, luckily. It looks awful but I don't think it hurts them. I don't think there's any way to break them of it, either, so I just let them be if they have that nasty habit. But no doggie kisses from THAT dog!
Hoomom who was blessed with Jack. RIP Sweet Cynda 6/3/10, loving Lexie 9/13/13 and Jack, 3/22/16.