I suspect you are seeing the difference in care prepping the down by the supplier. Too dirty and it smells. Too clean and it breaks down.
It is interesting in that one way to make down puffier was to dry clean it. The solvent stripped the oils in the down and it became very puffy but broke down fairly rapidly. That is where the warnings about how it is cleaned comes from. I assume the industry checks for this now or the Chinese would be doing it to increase profits. That leaves me thinking their answer is just enough cleaning to get to loft specs. Since cleaning costs money I would expect some sharp folks figured out what class of down gave the highest profit and that is what they produce. I know that is done in similar industries like grape and olive extracts.
Free advice worth what you paid for it. ;-)