I had a bearded dragon that got impacted. The vet recommended putting him in a critter keeper with a heat source and to watch him closely. We put him in a critter keeper and because we couldn't use heat lamps (melt the plastic) and I didn't have a UTH, we used a heat rock we had bought but then never used because I had heard not to use it. Well my lizard could barely walk but he was able to get on that thing for heat. He ended up with burns on his belly. He didn't live long after that due to the impaction but I did witness burns.
I work in a Petsmart and I will steer people away from heat rocks every time I see someone looking at them.
And its not a matter of the temperature getting hot enough to literally COOK a reptile. People have experienced temperatures in their racks reach a little over 100 and their snakes suffered damage due to high temperatures or so I have read. If you put one on a thermostat or rheostat, then like a UTH, it can be safe, but MOST people walking into a pet store for their first reptile are not going to think of that because they haven't done all the research. They haven't talked with hobbyists about how to properly keep their new reptile. I have actually had to step in and correct my department manager because she was recommending the wrong kind of bulb or wasn't recommending UVB lighting for bearded dragons.
And I'd say over half the people wanting to come into the store to buy a bearded dragon don't want to spend $15-25 on a UTH, and then another $20 on a rheostat when they can just spend $20 on a heat rock. Why spend $12 on a good basking bulb for your new bearded dragon when you can spend $8 on this cool blue light instead.![]()