I did a similar experiment a few years ago, using dry dog food with zippered freezer bags (Ziploc brand) and with OP sacks (Loksak brand), and my Labrador/Golden Retriever cross dog (service dog reject). I was concerned because after I packed my dog's kibble into single-serving freezer bags, I could smell the food through the bag, and my nose isn't very sensitive. My results contradict this study.
I tried two layers of freezer bag. That worked for me, but when I left it on the floor, my dog immediately pounced on it and tried to chew into the bags.
I then put a single freezer bag with dog food inside an OP Sack and left it on the floor. My dog walked right by it several times without noticing the smell.
I ran this trial several times, with pretty much the same results. The only difference was that my dog became conditioned to associate a plastic bag on the floor with food, so after a couple of replications he started sniffing the OP sack before moving on. He still did not detect the food inside.
Admittedly, my dog, although of a hunting breed, has never been specifically trained to follow scents, but his food, for him, was an extremely powerful motivator. To motivate him more, I ran the tests just before dinnertime (which caused a lot of barking). Since he didn't smell his food inside the OP Sacks, I had to assume that the OP sacks are at least somewhat effective. The single freezer bag plus OP sack was definitely far more effective than doubled freezer bags.
It may be that those "controlled substances" have a more powerful smell than dry dog food. Or it may be that my dog has a lousy sense of smell. But at least with the OP sacks, I didn't have to worry about my dog getting into his or my food!
Since bears reportedly have a much stronger sense of smell than do dogs, both this study and my one dog study may be moot. However, I have read several anecdotal reports from reliable persons of a bear walking right by a hanging OP sack without investigating it (in most cases the OP sack was inside an Ursack). Maybe the bear wasn't hungry? Or had a head cold?
I will continue to use odor-proof sacks, although I would never rely on them alone, only as a supplement to my Ursack or canister. Nor would I use them to store food inside my tent. But I have demonstrated to my own satisfaction that OP sacks keep my dog out of the food!
PS: I fully agree with others above about the OP sack seals; they're horrible! I plan to try the Nylafume bags, although my dog won't be with me this summer.
I'd love to see the results of a similar trial using mice or other rodents. I had one get in my car one time while I was on a 3-day backpack trip; it ate most of an apple I left on the front seat. It also evidently investigated an OP sack in the back of the car that contained food for a subsequent trip. There were mouse droppings nearby, but no evidence the sack had been chewed. I never figured out how the mouse got in my car, but another backpacker reported the same thing happening at the same trailhead a week before.