My observations have been that deer react to what they have not become accustomed. In very deep woods with little human contact from actual humans to scent from human habitations..., they seem to be more easily alerted to human made scents at lower concentrations.
In areas where the deer are close on a regular basis to human dwellings and roadways, they seem to be less cautious of human scents, unless the human scent is very strong.
Following that observation, I also have found that deer are also more cautious around scents that suddenly appear, no matter how "natural". So in a area devoid of apples, dropping apples on the day of the hunt or using "apple scent" seems to have undesired results, as would deploying "yellow corn" scent in an apple orchard.
This is assuming the white tailed deer of Maryland and Virginia that I have seen in the wild are typical in behavior to all Odocoileus virginianus.
I smoke my clothes with hardwood smoke, as I have also seen a buck react to the scent of smoke clothes with curiosity, not caution or flight, AND..., I pay attention to the wind direction. This past season's results were three deer at under 100 yards.
I have also noted that deer react to quick motion, especially with a noise, than with very slow motion. So if I raise the rifle quickly, and cock the piece with an audible click..., the deer flee, but a very slow raising of the rifle, sighting it in, then cocking the piece..., the deer have looked right at me at less then 50 yards, as I shot them.
LD