Just a few days 'til Christmas!

We have just a few more days until Christmas. This year should be fun for us. It looks like we will have a white Christmas here in Omaha, Nebraska, which is always a lot of fun. We plan to fill Lady and Zoe's stockings with treats and a couple of toys. Lady doesn't really play with toys, but I hate to only get treats. Although, she would love it, I'm sure. She LOVES to eat just about anything. Unfortunately, that also includes cat poop and our other dog's poop. In fact, both of our dogs eat each other's poop. I know this is gross, but we can't seem to get them to stop. I read a book that said it is abnormal for adult dogs to eat any poop and if they do, it's probably because they don't have enough human interaction or they are just plain bored. With my dogs, I really find that hard to believe. We play and cuddle with them all of the time! And when we aren't playing with them, they are playing with each other.
Can anyone else offer any advice on this gross habit? Personally, I think the dogs are just in the habit of it now and they can't break out of it. I don't see how I can follow them around the yard all of the time to make sure they don't eat poop. What should I do?