more and more I'm realizing that reptiles do better when given everything in gradients, including basking temps and humidity. I set my beardie's tank up so that the basking spot gets up to 130 or 135 directly under the heat lamp, and so the further he gets from it, it decreases. He usually hangs out around 100 degrees on the basking spot, but often he will go right under the bulb to warm up quick or aid in digestion. I'm working on the humidity gradient right now. I keep my beardie and my uro on soil because I find it to be the best substrate medium for both species, since it's something they'd naturally have and use in the wild. I'm trying to find just the right thing to use for my beardie, but I want to have a really low flat hidespot that he can dig under...basically just something set on top of the soil. That way, when I put water in the soil (about 2 times a week....it keeps it together and the top layer is dry in hours, so now, it won't cause high humidity all over the tank unless you go overboard), that hidespot will retain moisture and humidity, so my beardie can go there if he needs higher humidity. I suspect they use similar things like that in the wild.
My uro on the other hand has something very close to a real burrow in her cage. When I get her new cage done I'm going to load it with about 8-10" of good soil and let her construct her own burrow. Uros are intreging because they come from such a hot, dry climate (her basking spot temps are as high as 140 or 145), but after being out only a few hours each day, they retire to burrows way below the surface that are very humid. That's something I've been trying to recreate in captivity.
From what I have gathered parasite problems and problems with impaction and constipation are a result of the conditions we keep them in in captivity. If we give them everything that they would naturally use in the wild to overcome these problems (like gradients of everything...especially having a basking area of really high temperature to go to). A lot of people I have talked to on the subject testify that the only times they ever had parasite or impaction problems were when they were keeping their animals in sterile environments with temps that are comparitively low.
I don't expect people on here to take my word on it and go and do everything I've been talking about, but it's just food for thought. I personally don't think the sterile way is necessarily the best way.