I thought the five dead snakes turned out to be from the substrate...
Thanks for the tip, though. I've got two glass cages that'll be on the opposite side of the room from my rack. The three will go in the rack and my current two will stay in the cages for the time being. I've got a bottle of GermX right next to my cages, always sanitize before and after I handle them. I read somewhere that reptiles can carry salmonella on their skin, don't want to get sick or get them sick from something I've got on my hands.