The only way I know to curb this would be to set up leashed situations where there is food on the ground that she needs to ignore, and you teach her that your treats are better than the crap on the ground. Then, during this re-teaching period, you will have to make absolutely sure she never has a chance to eat garbage stuff off the ground, or else your training will go nowhere.
Still, RRs being the chow hounds that they are, unless you're going to go around the beach and clean up the bones, fish, and rice that's left there so she can't go back to it, I suspect that she'll ignore it, get the treat from you, then go back and scarf it down later.
Or, you could use a wire greyhound muzzle to physically prevent her from eating the stuff.
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