I believe some dogs have a "colder" nose than others but i also think they have to be taught (or learn on their own) to use it in many different situations. In my opinion if there is a fresh track next to an old track, most if not all dogs would take the fresh track, so i think availability of game ...

nice lookin dog ya got there, whats she out of and who is she bred to if you dont mind me asking? She looks alot like an old smokey river dog I had.