Jason is right, if you depend only on the quality of the heater to protect your snakes for you then you are just waiting on an accident.
While the heat pad probably malfunctioned and got super hot, had it been on a thermostat, this burn would not have occured.
A dimmer can be had for a few dollars, and a nice little on/off thermostat for less than 25.
Any manufactured product will suffer from occasional defects, that's simply a fact of life, but it is up to you to take the proper precautions to protect yourself from potential hazards.
If you think everything is just fine running flexwatt and such with no temp control at all take a look at this picture.
When I when I discovered and unplugged that heater I used a Raytec temp gun to take a reading on it. It was 192°F.
If you want to read the rest of the story about that instance it is
on this page .