You can train her to not eat her own poop.
Reason #1: The dog food your feeding her does not have enough nutrients in it that she needs.
Solution: Change to a better dog food and see if she stops.
Reason #2: She thinks her poop "tastes good" or it was a learned behavior from another dog.
Solution: Clean it up every time she poops before she has a chance to eat it.
Complication with #2: This method is complicated by the fact you have multiple dogs, I'd try training her to stay away from the poop and rewarding her when she does so. You do not want this behavior spreading to the other dogs.
Reason #3: Territorial battle.
Solution:If she's just eating her own you can semi-rule this out but still check to make sure that all the dogs socialize properly else introduce the two in a non-threatening area with plenty of rewards for good behavior, when bad separate and re-introduce again rewarding the good behavior.
All of these are just as Easy or easier then cleaning her mouth when you want to play, or that embarrassing surprise when she licks a guest and she has poo on her tongue.
But "She's just eating a bit of poop it wont hurt her." Wrong, this behavior greatly increases her chances of tapeworm, heart worm and about a dozen other life threatening illnesses. If you care about your pet then take care of her.