Interesting strategy. I was recently researching the chemicals that cause the bad smell of farts and came across the chemical called Hydrogen Sulfide. This chemical is also found in rotten eggs, which makes them smell so bad. Maybe if I took a whiff of a home made rotten egg, I would be sure whether or not my body emits hydrogen sulfide. If I can smell the rotten egg, then my body doesn't emit it. If I can't, then the chances are that I am immune to it because of my own body emitting it everyday right under my nose. Then we can do some research on what bacteria produces this gas and so on. This strategy can be applied to many other chemicals. If you can't smell them, then your odor is made up of them. But be careful, these chemicals are very harmful and can kill you if inhaled in large concentrations.