Nutritional deficiency may be the culprit sometimes but not all the time. I have some here that eat stools also and it is by no means due to a nutritional problem. It drives me nuts too!
I have no problem cleaning dog poop, and I have no problem cleaning dog vomit. But let me tell you, when one comes back in the house and vomits dog poop up, ooohhh boy is that another story! If hubby isn't here to do it for me, I have to clean it up taking a 2 minute break every 1 minute otherwise someone would have to be cleaning MY vomit!