Why the scene with Sam isn't realistic
As everyone knows, the sequence where Sam attacks Clem is pretty damn traumatic, and adheres to what would really happen in a situation like that...
...except it doesn't.
I've been in touch with two different dog specialists, and I described the scenario in the video game to them right down to the last possible detail. On both occasions, they said a feral dog deprived of food to that extent would simply tear into Clem on sight, and not play nice before snapping without warning...especially a dog that had once been domestic. As for the situation with the can of beans, they explained to me that if a human gets between a wild dog and its food, the dog might injure the human at first, but return its attention to the food itself. Sam would only bite Clem (as he initially did in the game), and then focus on the can...and NOT continue to attack her with the intent to kill.
A dog behaving exactly the way Sam did in the game is freakishly rare, with rabies or some other mental defect usually playing a factor. It goes to show how needlessly nasty the scene really is.