you are so eager to knock the dirt, and i haven't seen one piece of evidence that you even understand it...
heath problems like this have little to do with substrate, and more to do with geneneral husbandry. respitory infections have more to do with temps than anything else. you can get resp infections keeping your animal on cool damp newspaper, or cool soggy seeds, but it is not the fault of the substrate, that is the fault of the keeper.
and a soil substrate has nothing to do with tumors either (neither does most husbandry, they are in most cases undetectable and unavoidable in the early stages).
mike does his own modified thing, he has taken a bit of info from here, some from there, and has his own method. i am expecting him to have some mixed results, but that is his choice. tumors are just an unfortunate event. his diagnosis of respitory may in fact be incorrect altogether, as it is easy to confuse any number of "symptoms" with any number of problems.
he really hasn't shared enough details of the overall setup to reliably offer an "internet diagnosis" but you want to immediately attribute it to dirt and soil, hastily and incorrectly.
and on top of that, the implication ("HELLLOOOOOOO...."
is that folks here are "suckers" not to realize it.
i think you are mistaken, and you should look at substrate, husbandry, setup and temps from a more logical perspective.
keeping Uros on soggy cold substrate of any type would be harmful to the animals. that is not what we are doing or recommending, even in the slightest.
if you are a true believer, then break down your reasoning and let's discuss it (again), but don't just pull the trigger everytime someone has an unrelated husbandry problem and say "it's the dirt!".
that is too much chicken little, and not enough chicken logical 
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robyn@proexotics.com
Pro Exotics Reptiles