Hello Jungle Jim,
The theory behind this Rattlesnake proof snoring ring is that the Rattle snakes are afraid of King snakes, and rightly so as the King snake will eat a Rattlesnake. When a Rattlesnake sees the rope, it doesn't take any chances, and avoids it, as it could be a King snake.
Some people think a snake just uses it's tongue to guide it's self, but they also have eyes, at least the ones I've seen. I don't think the color of the rope really matters, as King snakes come in a variety of colors. The most popular King snake in my area are the Blue Indigo, which is black, then there is one that is black with yellow, and there is the Milk snake which kind of resembles a Coral snake.
I also used to trade snakes, and have handled hundreds. When I would put a small King snake with a bunch of big Rattlesnakes, they would get out of it's way pronto quick. I'm not sure if this trick works or not, but it does have a lot going for it.
Homar P. Olivarez