I'm with Bill C. on this. I smell deer a lot. All deer give off some odor when passing. Rutting bucks have a certain & very distinct smell, and the more into the rut, the stronger the odor. A doe in heat is so obvious that only those with broken snifters would miss it. A wounded deer has a certain smell, depending upon the hit. A scared deer emits a different kind of smell when it takes off. My friends think I'm crazy, but I can smell deer and have tracked wounded deer this way. Bears have an entirely different "musky" (not dirty) smell. All of these odors are wafted in the breeze to those on the ground, not in trees, so I'm mainly talking about ground hunting or "sniffing".
Where I hunt, rutting areas, when I start smelling does in heat, it is "time".