Well, I don't know what you mean about squirrel. Had it, thought it was good. As for raccoons and other predators/scavengers, I've had this discussion before, although more dealing with an all-predator environment than cannibalism.
The vitamins, fiber, and such from vegetable matter can only go through so many digestive tracts before it becomes worthless. You don't often see predators eating other predators, even of different species.
Case in point: Lions and cheetahs. A lion will kill a cheetah if he can in order to cut down on food competition, but he won't eat the cheetah. The reason is that there is little in another great cat's body to sustain him. A gazelle/zebra/whatever ate some grass. Fine. The cheetah caught the gazelle/zebra/whatever and ate it. Again, fine. The lion catches up with the cheetah and kills him. Now what?
The lion will not eat the cheetah. Why? Because all the nutrients in the cheetah's body have already been processed twice and are mostly depleted. The same goes for cannibalism of almost any species of itself. If a human ate another human, someone contended (in one of these threads, there are way too many) that a human body has everything another human needs. Not so. That human body has already
used almost everything that another human would need out of his food. It would barely nourish another human at all. In fact, being human, it is more likely to have diseases that will affect another human than any given herbivore prey animal is. It is illogical, immoral, impractical, and unhealthy. Now are you still going to persist in this foolishness, or am I going to have to just start flaming?