What was the point of this, post? None of you, not one apparently, has seen either the Coastal or Inland BD in the wild? Rankins? Wow I bet the Panther Chameleon community would laugh (in general not just KSnake). And the saltwater fish one too, because we spend so much time RECREATING. Now this thread is ridiculously long and I haven't completely followed it because it's rather silly but I did read most.
(I keep three reefs, panther and various horned chameleons ((Kinyongia (formerly Bradypodian) and Trioceros)), I've had many BD's and still do, obtained recently a turtle and I'm an avid vegetable gardener. I'm not an aficionado but at least I've BEEN there and seen them run around on rocks with clay in between (I had BD's at home then too so I was very interested, some of them seemed to be rankins dragons but impossible to tell as they were somewhat hard to photograph on red terrain). Trust me, it isn't tile. Nor is is soil per se. Most of you need some kind of disclaimer to advice, so here it is.)
If you recreate nature obviously you want to make the P. vitticeps enclosure with a particle substrate. This keeps the immune system up (presence of bacteria vs. not present [chemical scum is worse than bacteria for obvious reasons IMHO]) but remember that the rocks are more or less "emerging" from the ground. IT IS NOT THAT DRY GUYS! It rains for days and days in part of the year in Qland and NSW, they are found in areas where this happens (and farther out from the coast) and it's not unusual for humidity to stay high for days at a time.
If you like to keep things kennel sterile. Use tile. There you go. No bacteria, no good bacteria and no bad. congratulations. please don't see this as bashing as I will always keep dragons who just plain eat the dirt in this setup. it's just too sterile, as a reef keeper this scares me because of chaos theory. lol jk
The "actual" bearded dragon from the coast deals with leaf litter as far as I could see. only saw one the whole month, was perched on a tree (vertically) near an area where we were spotting swamp wallabies. Yes, swamp. Seemed more like a beautiful rainforest than Alabama/Louisiana though lol.
Am I saying you should change your methods? absolutely not. But I'll always use HDepot mix (didn't know robyn was attributed with it, so thank you very much. and keep working at fedex I'm pulling for ya'll, great thing for the community) and anyone who does is recreating a natural habitat. Anyone who uses non-particulate is not.
Should be noted, I never saw a dragon on "sand" in fact Australia is basically sandy at the beaches only, with hard packed (but easy to loosen) soil that is infertile (compared to Kansas where I am from everything is) and easy to break apart. They also tend to take shelter in a "rockstack" so tile is absolutely fine. But don't dog my methods, I believe my dragons are very happy, seems like that's the only thing these forums do.
Btw, the Carpet Pythons are to die for. Almost ran over one on a bike. For those of you who would rather discredit my reasonable opinion by saying I wasn't there, proud Alum of People to People Eastern Australia Student Ambassador program 2004.
"Don't hate. Recreate."
And a great reef adage (to apply to Robyns soil idea) "The solution to pollution is dilution!" In an abundance (a bag of soil), Bacteria balances. It's what it does.
Since soil doesn't impact as bad (they taste the dirt no matter what, right? it's dirt and if it's passable then no problemo, no? sand is inappropriate and unnatural to be in their body though from what I've gleaned over the years, use very little. they also don't live in a dry peat bog believe it or not! dry peat is horrible for ingestion too, worse than regular soil for sure. again IMHO)
So "Take action against impaction!" 
The more clever way to go about this thread (*cough*flame*on*proexotics*cough*?) would be to state the best brand/coolest tile. and the most efficient/natural/clean soil to staple your mix (make me happy and tell me there's something I can plant my potted plants in that my beardies will like... lol).
please don't see this as me bashing those who care about cleanliness, this thread has ticked me off for too long because of "bacteria"=bad? that's foolish. More good bacteria live in soil (good soil that's established) than bad by a long shot. Helping your bearded by giving him his G-d-given immune system.
Please add a sprinkle of humbility to this where needed, I'm an avid keeper but don't really post because I'm easily riled (ya ya, Kansas has an accent. my location means I know dirt though).
Oh and for you "bubble-dragon" sterile cage fellows, how do I get bacteria free potted plants for my Ambilobe's, with tile? How do I get bacteria free live-rock for my BTA tank?! Do you have a bacteria free shower even? Or does it have bleach residue, cleaning products and grime from chemical/tile use bacteria that survives? This is how you keep your animals on residue? sorry that I don't agree. Do you have a light that shows this stuff? shine it in your beardies tiled world. Now get a bacteria light, shine it on my soil. I dare you. I also dare you to make a real productive thread out of this hot mess of stinky opinions.