I see! That does make my impression on them a bit brighter but I wouldn't try petting them anyway. Snakes are beautiful, and most of them are harmless, but I'm rightfully afraid of them. Perhaps my ancestral genes are at work.
I didn't realize before it's a rattlesnake species (and with horns no less!), makes sense to me now — when you were saying they shake and sink into the sand. I think I've seen other rattlesnakes do that too on Natgeo or discovery.
Sidewinders really like the sand. Most of the diamondbacks around here are in the 'harder' rock desert as are most of the Mohave Greens. Rattlesnakes all, but different ranges.