As a 10-year Arizonan who has been "buzzed" by rattlesnakes WAY more times than my little heart can take, I think the rope thing is an old wive's tale. Rattlesnakes can, and will, wind their way up tree branches during spring bird egg season (imagine how freaky it feels to have one rattling at you from the branches of an oak tree!), and I see no reason why they would hesitate to cross a rope on the ground. I've seen them cross wires on the ground...
They are pit vipers; the pits on their faces sense heat. Unless they're scared and angry, you can put something without heat (like a broom) in front of them, and they don't strike at it (they usually just move away from it). Again, unless they feel threatened or angry, they won't strike at something huge, like a human, because they know they can't eat it, and it'll use up their venom supply with no food reward.