From context it seems to mean that cocaine itself isn't detectable, but that a person who has consumed cocaine can be detectable by odor. I can't find anything backing that up though.
and I don't see how drug dogs trained this way would help detect cocaine in, say, a suitcase, vs a person who had used cocaine but was carrying none with them.
That's how i read it at first, but it could also be that cocaine goes through fermentation during it's extraction, and that if that's done near human settlements, air pollution contaminates the final product, making it detectable.
