I totally agree with you about the potential for loss or harm to the critters. That would be a nightmare. I'm pretty compulsive about checking and maintaining proper temps. I usually check my ambient and hot spot temperatures a couple of times throughout the day. I also use ultratherm uths which really don't get hot enough to burn the critters. Even without a thermostat, or in the event of a t-stat failure, they don't get much over 100F. My snakes also don't use their hot spots very often. I was just checking on them and only 1 of 8 is resting on a hot spot. The others are on the cool side or perching on a branch or shelf. I'm by no means knocking herpstat. I've just found that I can achieve the same results more economically.