Also, I decided to get more into this. Sorry. None of this should be new to you, though.
Ferrets are stinky because they have musk glands, not because of diet (although I'd imagine that diet allows for the musk to be produced). I didn't have to use Wikipedia for that one. They are of the family Mustelidae.
Mustelidae. It's a natural odor and not something to flaunt when you don't have it. Parents of stinky ferrets are doing nothing wrong, even if they use store-bought food that you dislike. Depending on where you got your ferrets, they may have had their anal glands removed to begin with, which could explain the decrease in smell. The majority of ferret owners don't know that the procedure ever happened. Perhaps you just lucked out with your pets, and they just don't produce musk at the levels other ferrets do. Some dogs have anal glands that peel the paint. Others have anal glands that don't knock you off your feet (although they still aren't pleasant....).
I'm big on knowing the differences between "wild ancestors" and the animal you call your pet. My dog's ancestors were wolves. Do I go out and catch a rabbit to feed her? No. It wouldn't necessarily be a good source of nutrition for her. Plus my pet rabbit would be offended. Petsmart does stock junky food, but they also stock food that is perfectly acceptable for small mammals. You don't have to buy your ferret the candy coated treats. To be honest, the worst treats are down the hamster/bird aisles, not the ferret section. I'm no veterinarian, but I regularly scrutinize the aisles at Petsmart and haven't seen anything in the ferret section that is as bad as the pocket pet 'trail mix' foods.
I'm not going to try and sway your opinion, but here is a link from a veterinary school:
http://cvm.msu.edu/hospital/service...cation/feeding-and-caring-for-your-pet-ferret.