Here's a quote I got from www.boa-constrictors.com/com/com.html

We strongly discourage people from using ground heaters, especially those with a high wattage, because the snakes lay on them and dry out. We have received several calls from people seeking advice, because their python was having a bad shed and looking very wrinkled. These people swear that the humidity lies above 60%. Right, but not immediately on the ground heater! Measure that spot sometime, and you will be very surprised: 35% or less are no rarity. Unfortunately, the snakes love these spots, because they are nice and warm. They are simply too stupid to realize that resting on a strong heat pad or heating cable is slowly but surely killing them.

Other keepers use ground heat to place the water bowl on top. This leads to nice and warm water, which makes for an excellent breeding ground for bacteria. We have thrown out all of the heating cables and mats years ago, and we have not regretted this once.

The best way to heat the enclosure is by the use of an infrared heat source (available with 60 to 250 Watts), which does not emit any visible light.
So which is it? Do CHE's dry out the cage more or do UTH's?

I'm so confused!