ORIGINAL: DaveH
Breath is a BIG giveaway in deer scenting you. While baking soda is a good idea prior to hunting, it's impractical to carry it with you IMO. Keeping your mouth closed and breathing through your nose is the best solution. It's also the cheapest.
I'm not sure exactly what difference breathing through your mouth versus your nose is really going to make. Your breath is still coming out of your lungs, it's just going up another inch or two before it comes out. There isn't any less of it coming out either. and why would the odor from your breathing not travel as far as the rest of your scent? Color me confused on that logic.
I have to admit that when I first heard of the Gum-O-Flage idea it struck me as rather ridiculous however the more you think about it the more sense it makes. Your expell a much greater amount of gas from your lungs by breathing constantly than you do odor that simply emits from your skin while sitting in your stand. And unless you can hold your breath for about 3-4 hours at a time that's not likely to change anytime soon.
In the end I'm not completely sold on the idea, but I certainly think it warrants more attention that some people are giving it.