Breath odor is a great illustration that most of us should be able to relate to in terms of detectable odor.I have thought that most of your sent comes out of your mouth. In his book Come November, Gene Wensel wrote about a couple guy's he knew that went vegetarian during bow season, so they did not smell like a predator. I phoned Gene and asked for the guy's names and numbers because I wanted to learn more. One guy was from PA and the other from Mich. These guys were sent extremists. They wore two layers of sent control clothing, went vegetarian., did not put on there hunting clothes until they parked the truck and so on. They both felt that this helped, but they both said they still have deer smell them. Now I agree that a hunter should do everything they can to reduce odor. The biggest buck I have ever shot was on a trail 20 yards down wind. I was 20 feet up in a tree, the buck smelled me, but probably did not realize I was that close.
Bad breath comes from poor oral hygiene and even a human nose can detect bad breath. If you are face to face with bad breath its actually repulsive. If you are a few feet away, you might still smell it but it doesn't make you gag. A little further away, and you cant smell it at all.
On the other hand, you can suck face with a clean mouth and it's sweet.
Compare that to that invisible line out there where our odor dissipates and is less alarming to deer. We can reduce our overall odors to the point that a deer 150 yards away may not bolt when they get a whiff of us. That same hunter with poor hygiene and odor practices might get busted at 300 yards. Those fringe deer are the ones that may or may not end up in our shooting lanes...if they didn't already smell a rat when they were 200 yards away.
It's not about becoming completely odorless, its about improving the situation in anyway you can.