Some dog's have the very NASTY habit of eating poo.... believe me I know, now there are several different types of med's that are out there that can help in preventing the nasty habit, however I really don't know what they would be called in your country or even where you might find them, so I would talk to your vet. Yes eating poo can be harmful in several ways, it can be mild which may include vomitting, to severe that can include a digestive block. What I would do to start breaking this nasty habit, or at least try to control it a little bit, is to make sure your dog knows it is wrong, that means telling them no, and asking them to spit it out. We catch the one that we have that does it, and when we tell her to drop it, she does, but I know we don't always catch it. She knows it wrong, yet as grose as it is, she has developed a taste for it.
As for bathing your dog too much, there are some that will say yes, and some that will say no. When I worked at a vet clinic, one of our pet shampoo rep's, had a training session for us, and during that time, she mentioned that bathing a dog everyday was fine, as if we were taking a bath ourself. However I've also heard that by bathing your dog too much you are taking away from their natural oils. Now over here there is a vet that doesn't believe in bathing her animals period....now I could never do that.
If your going to bath your dog more, specially in the winter, be sure the house is warm, and that they are completely dried (usually needing blow drying) before going back outside.