In my experience, I've had beardies on sand for 8 years without a problem, and a childrens python on sand for about 15 years without a problem. It might just be bad luck that some get an inpaction. Plus I have always used sticks and things I find outside without 'cleaning' them and have never had a problem either. I think it's kinda like if you use antibacterial EVERYTHING around kids, they never get exposed to anything so their immune system can work, so one day when something comes along that wouldn't effect normal people, they end up with some huge reaction (ok, I know it had nothing to do with herps, just my opinion)
And when it comes to cleaning, I just use a kitty little scoop to get it all out. I think if you can't be bothered changing it all over regularly, that's when problems can occur. Plus I think keeping them on newspaper is terrible, yes it's easy to clean, but it provides no traction, and in the case of things like beardies, it prevents them carrying out normal behaviour, like digging, and I think that's cruel.
So none of that is gospel, just my thoughts.