As subject, can the Unchained Rogue's Follow Clues rogue talent be used to substitute Perception for Survival to track by scent?
Follow Clues (Ex): A rogue with this talent can use Perception to follow tracks as per the Survival skill.
A creature with the scent ability can follow tracks by smell, making a Wisdom (or Survival) check to find or follow a track. The typical DC for a fresh trail is 10 (no matter what kind of surface holds the scent). This DC increases or decreases depending on how strong the quarry's odor is, the number of creatures, and the age of the trail. For each hour that the trail is cold, the DC increases by 2. The ability otherwise follows the rules for the Survival skill. Creatures tracking by scent ignore the effects of surface conditions and poor visibility.
My instinct is that it can be used by a rogue with the scent ability to track by scent with Perception instead of Survival, but I feel like it's a little ambiguous.
I don't see any reason why not -- Scent lets you follow tracks by Survival, and Follow Clues substitutes your Perception (which Scent extends the scope of anyway) for Survival.