What is Wrong Turn the movies about?

i have watch all 3 of them and never got the point of the movie. Why are the cannibals all deformed and how come they kill and eat people? Did people make fun of them or something? Why don't they eat the animals in the forest? And who is that old guy in the first one whos at the gas station? Also i don't get why they always send one cop! Whoever responds to my question will get 10pts!