Every ground beef I've ever purchased has a stated fat to lean ratio. So, 100% beef fat is not ever gonna happen.
As per the 'patties are made of dog shit' claim... the difference in cost between beef with a stated location/content (e.g., sirloin, or chuck) and the generic ground beef is so low I don't see how your claim could be true. And if you're actually worried about that, just buy patties with a stated location of the cut.
People don't care much but a lot of food is very far from what you'd expect. A butcher's minced meat isn't the same as a supermarket's minced meat despite having the same name, some of them are barely 50% meat
As per the 'patties are made of dog shit' claim... the difference in cost between beef with a stated location/content (e.g., sirloin, or chuck) and the generic ground beef is so low I don't see how your claim could be true. And if you're actually worried about that, just buy patties with a stated location of the cut.