Old Methodology - New Marketing
There's no doubt that the treatment is genuine. But its effectiveness is doubtful.
The process is a fogger misting a chemical throughout the interior of the vehicle. The chemical is an encapsulation product similar to the consumer product Fabreze. An encapsulation chemical must actually make contact with bacteria or whatever allergen is growing in the air ducts. The problem is, misting fails to penetrate to the more unreachable areas, thus fails to kill all of its targets. Once the liquid (mist) dries, it is ineffective. That's probably why the growth of returning allergens occurs on the petri dish. They were the survivors continuing to grow.
That's why the most effective sanitizing agent is a gas, not a liquid mist. Ozone gas is able to penetrate all of the areas inside the ductwork, as well as other areas that are unreachable that misting cannot treat.
And unlike a chemical liquid (mist) that is deposited on the entire interior passenger cabin, ozone leaves no chemical residue. Chemical misting residues risk having an adverse reaction if the skin of someone overly sensitive comes in contact with the chemical residue.
So, I suppose the treatment represents a "genuine" attempt. However, it fails to really eradicate the unwanted allergens. I suggest using ozone on interiors, with the air conditioner set on "max cold" (a setting that continuously recirculates interior air throughout the ductwork), with a treatment time of 5-10 minutes, depending on the strength of the ozone generator output (in grams).
Hope this helps...
-Steve