IMO, I think both occur, Art. I know I have a friend that I've hunted with many times. He's had me review what he does for odor control more than once and he gets winded regularly. I can't find anything that he's doing "wrong."
Then, I've seen others complain about how they got busted and you just can't beat a deer's nose, period, but they were frying bacon and eggs, while drinking coffee in their hunting clothes before heading to the woods.
As a side note, I drink way too much coffee while writing. I never drink it before I head to the woods, and rarely do within 24 hours of hunting, period. You just can't get that smell out of your throat. I don't stop eating red meat or anything like that, but I do avoid onions, garlic and any foods that give off a real strong odor.
Personally, I don't think there's a product out there that's a cure all. Personally, if I don't do everything in my power to treat every item I'll be bringing in the deer woods, I'm going to get busted.
At the same time, I'm under no delusions that you can stop human odor production. I think it's more like Nov's experience with the shadow hunters. You can make it so not enough odor gets to the deer that it alarms them. Is it that they think you're a mile away or were here 3 hours ago or that it diffuses to the point that they can't smell it? I don't know which, but I suspect it's one of those 3.
Jumping off topic, as mentioned, I think there are a lot of reasons why using dogs to try to disprove if odor control works is flawed. One of the biggest is that dogs are trained to react to even the slightest trace of the scent they're search for. Deer aren't. In most areas, if deer flipped out every time they picked up a hint of human, yote, wolf, bear, big cat, dog or any other predator's odor, they'd spend large portions of each day running scared. I believe they more or less expect to pick up some traces of predator odor, particularly in certain areas (fields, for example. Between the farmer and predator activities there, there's some trace of "alarming" odors there more often than not). I believe it's the level and/or perceived "freshness" of the odor that turns deer inside out, where as a dog will zero in on the freshest trace they can smell. Obviously, I can't swear that's the case for deer anymore than I can answer which one of the 3 potential reasons I gave above is why deer after deer seemingly downwind isn't busting me is the case, but it makes sense to me, at least. Frankly, it doesn't really matter which one it is, as long as they aren't turning on a dime and going on a death running away from me