AbdulAlhazred
Legend
I dunno, I never really thought of heroes as 'rippling with power' personally. I guess it depends on the levels of the characters and the particulars of the genre of play. I wouldn't normally think of heroic tier characters in this way at least. Epic ones, that seems more like they'd be easy to pick out in a crowd of normal people. Paragon is a bit less definite.
I guess I might be more inclined to handle it more from the other end. Your average guy isn't going to notice the 14th level ranger sitting at the table in the corner. The fat barkeep, who knows a thing or two, on the other hand is quite aware that he's not your average traveler, but still doesn't really know any accurate information about him. The Ring Bearer on the other hand, and his fairly perceptive and somewhat experienced comrades, can see what they're looking at and tell that power lurks under the dirty cloak and muddy boots. The rest of the townspeople of Bree? They just see some slightly disheveled wanderer from strange parts.
So, a character can use "Read Aura" to suss out the higher level figures from the lot, even when they're not obvious. Streetwise or History might also obviously work to let you pick out a face that is notorious or famous.