You will not find a better piece of music to set the scene for creepy hillbillies. Especially if you watch the movie first.
I should probably point out that I (and all my players) were raised in West Virginia, and have heard dueling banjos a thousand times - occasionally live. While I probably will use it, I was hoping for some other ideas, too
Knowledge (local) being trained only, and not a class skill for many classes, means that your average human may well not be able to identify other humans! This may explain the exceptional quantity of half-human hybrids.