Coprophagia is certainly a disgusting habit but it's actually a fairly common one, believe it or not.
We often don't have a good understanding of why some dogs engage in this behavior although it's rarely related to deficiencies in the diet. Many puppies go through an oral stage in which they explore everything with their mouths, sometimes ingesting a variety of non-food items, including feces. As they mature, though, the majority of pups eventually learn that food tastes better than feces and that's the end of it.
But for those dogs who continue the practice, there may be a compulsive component as to why they don't stop. It's almost an addiction, in a way. And, as a result, it's often very difficult to break this habit as it is for most compulsions.
There are products on the market designed to make the stool even less appealing such as Forbid or S.E.P. (stop eating poop). Some people will add Accent or meat tenderizer to the kibble. Some owners swear by fresh pineapple which is also added to the food. Some people will try to sabotage the feces by adding jalapeno peppers or something really spicy to the stool in an attempt to discourage ingestion of feces.
Some of these strategies will work for some dog but they by no means will work for all of them!
Personally (and I do mean personally since I've had several dogs through the years who've done this and am currently living with one who does) the only thing that I've found that consistently works is to pick up the stool as soon as it's produced. If it's not there for a dog to ingest, then they don't ingest it.You can also teach the "leave it" command which works if she starts to eat the feces in front of you. This is a good command to learn anyway, in my opinion.
Of course, this methods will only work if you are present. I often recommend a basket muzzle when the patient is outdoors and have found that these can be quite effective although we're not really changing or modifying the behavior.
For my patients with this problem, I also encourage lots of exercise and quality time with their owners; boredom is not necessarily associated with this problem but it helps to rule it out by keeping the dogs active.
This can be an extremely difficult habit to break ....and a frustrating one to deal with as well....but I hope this helps and gives you other options to consider.
Her attempt to scavenge may be OCD related as well or learned behavior or an inherited predisposition. She may benefit from some of the options I mentioned above (such as increased exercise) but if she's hard-wired this way, then it's going to be really difficult to change her behavior. But, another suggestion would be use of interactive toys which will engage her mind and keep her occupied for long periods of time. If you search "canine interactive toys" on the internet, you'll find a number of choices.
I hope this helps. Deb