The problem with any test is the number of variables that we just cannot know (we guess, a lot, but really have no clue).
Does wind change things ? How much wind ?
Does heat / cold change things ?
Does humidity level change things ? Rain ? How much rain ?
Does time of day / sunshine, change things ( think thermals) ?
Does time of dissipation ( how long ago was the scent laid) matter ? How much ? Under what conditions ( above) does it change most?
Does how high in a tree ( or how low in a pit) we are change things ?
And we haven't even gotten to the source of the scent and possible ways to control it.
How do we measure any of the above ?
Using a dog ? Which may get bored, decide he doesn't want to play ? Decides he can smell it but doesn't care today ? Smells something else ( gun oil / bow oil / string wax / rubber boot smell ) and follows that but is not smelling the person ? That dog is a trained expert at following and finding, but nothing ever said it is truly just "human scent" it is following. Does that even matter ?
We are guessing. We have all sorts of anecdotal evidence to buoy up our choices, but really, they too are guesses.
" I had a deer walk up from downwind", well so have a lot of us, once while I was sitting on a log smoking a cigar, upset at the world and my meager life.
Did he not smell me, or did he just not care at that moment ? Does a person on the hunt smell different than a person just hanging out ? Does running a chainsaw change the game ? If you wander around, like G.Fred says, "looking for his lost wallet", does that change things ?
It has for him.... but why.
Smart as we are, We will probably never really know. But we sure like to guess.
ChuckC