Anyone without Prime 1 is going to be stumped, and even with Prime 1, they have to see you in both Mundane and Transformed forms to even figure out you have a duel identity. Prime 1 will tell them that you're Supernatural, as mortal auras are weak while yours blaze with power. In fact, I have a write up for most-Vampires can't without high-level Auspex powers, Werewolves are SOL, Mages need Prime 1, Prometheans also SOL, Changlings...lemme get back to you, and Sin-Eaters can do it automatically as they can see how much time you have left to live before you die of old age. In all cases, they need to observe both forms before they can even get a check (resisted by your Wits+Subterfuge-Sensitivity+Veiling). Sin Eaters get the extra caveat that they need to see both forms in a reasonable amount of time (10 minutes, round about).