I just had a theory that what if skinwalkers aren't really bad? Mabey when you encounter a skinwalker it will enter your body and give you all the shapeshifting powers and shit. And the prize for those powers would be your body wivh you will get in a new form and all your memories erased and the only reason they want you to go to the woulds with them is so they can share the awesome powers wich they posess. The part where they act all roboticly is just the state in wich they are sort of paralyzed by the joy of discovering these new powers. Silly theory but still interesting.
Skin walkers are normal people who happen to be shamans who murdered blood relatives for the ability to take the form of anything they wear the pelt of.
Goatmen are boogies who only want to scare humans and have no reported cases of harming anyone.
Fleshgaits are demon spawn who kill people and wear their skins with the intent of killing more people to provide disguises for their pack of nigh-invincible highly intelligent murder monsters.
Allergic to gold dust, doesn't kill but will make their disguise slowly peel away. Once they notice they'll quickly leave if they are around more than two people.
Fire will also fuck them up pretty bad if you can get them stuck in it for a few minutes, otherwise they'll just shake it off.
Other than fire, they are pretty un-killable to my knowledge. They can still feel pain so use that to your advantage, but be warned if you can't cause enough of it they'll just get mad and extra violent. Bullets are an example of something that pisses them off.
Skin walkers are known by different name in Latin America. I once took a vacation to Mexico and in my last few weeks I visited the country sides were most people are poor. The locals really believe in this stuff, somewhat convinced me. The skin walkers there use shapeshifting for bad doings. I saw how a freakn "Turkey" snatched someone's wallet. And the locals say that "pigs" and "dogs" go into people's houses taking anything but food. Also people of the area tend to wash them selves in isolated, partly covered shower/bath area next to their homes. Some "animals" always only wait for the women to go shower. They say they're just horny bastards who enjoy watching them.
Not likely seeing as how skinwalkers are people who kill one of their family members(or in some cases their whole family) in order to gain the ability to shift into any animal they wish as long as they have the skin. From what I hear they are highly terretorial, meaning as soon as you walk Into their land its leave or get fucked up.