I've been thinking about all the venomous snakes I have seen in my life and I can't really consider them much of a threat. When I was 17, I was sent off for the summer with my cousin to work on a ranch in eastern New Mexico. As we were being dropped off by my uncle, the rancher pulled up in his truck, unloaded a decapitated 5' western diamondback and proceeded to tell us that rattlesnakes were a big problem on the ranch. My cousin and I sort of rolled our eyes thinking this would be the only snake we would see all summer.

Naturally, over the next 2 weeks, I saw a rattlesnake a day. I rode over 3 different diamondbacks on horseback and once drove a small herd of cattle over the snake before my horse walked right over it. That entire summer, I never saw one of these snakes strike at us, cattle or horses. More recently, a 3' western diamondback was curled up beneath my office's outdoor card-reader. Not seeing the snake, I walked right up, held my card to the reader and opened the door only to notice the snake when the receptionist's screaming started to make sense. I know there are exceptions to this -- the aforementioned rancher claimed to have sprinted for 100 yards with a snake attached to his chaps at thigh level -- but I believe that unless you make an effort to mess with the snake, it's going to want to avoid you.