Inbar Rose said my leading answer, but depending on your setting garou, Garou can have certain (intentional) tells. That pianipiano player in the saloon will occasionally hide a call out to other garouGarou with his "nonsense words" in a song, ones that tag him as a Fianna. Those outlaws on the edge of town have the posture and attitude that sets them aside as Red Talons. AA Silent Strider might actually be tailing the group's pack and reveal herself when she knows it's safe. That governor over there uses the Silver Fangs symbol to seal his messages in wax (which might be a little too close to the chest in some areas, but if they have they clout...)
Gifts
- "Scent of the True Form" is the obvious one.
- "Eye of the Hunter" if they're in mixed company and the garouGarou in question weeds the group down, but not 100%.
- "Fatal Flaw" can reveal the vulnerability to silver, but that's not always a garouGarou for sure.
- "Sense Medicine" can detect garouGarou gift use which is a smoking gun but not in anyone's hand.
And those are just the results after skimming the level 1 gifts.