This is an absolute myth. Experience has proven to me that the personalities of snakes are as different as their colors. Sometimes a great basin rattlesnake doesn't rattle at all (note: some are not capable of rattling and some just don't) and will simply try to slither away when found, but be careful because body heat will almost always trigger a strike. Almost all snakes will vibrate their tails when they are grumpy. My Mexican black kingsnake and one of my corn snakes will vibrate their tails quite often. They would be quite noisy if they had rattles, yet they have never bitten. When you are hiking in rattlesnake territory, watch out where you step. Wouldn't you bite someone that stepped on you? Rattlesnakes do not want to bite in defense. They would rather save their venom for prey, but don't rely on a buzz warning.