They say that you can tell a Wraith by the way its eyes look through you, by the sharpness of its teeth and the lack of appetite for anything but beer. They say you can tell a Wraith by the way it kisses—as if it would swallow your soul—and the speckled scales down its back. (They don’t say anything about it being a little too late at that point.)
Despite the various folk tales that would seem to indicate otherwise, Earth has no such comforting lies about vampires. Forget sunlight and garlic and crosses; everyone knows that if (and pray God it stays “if”) someone is (becomes: that’s really the frightening thing) a vampire, you won’t know until you see them actually sucking someone’s blood.
The Earth people have both more and less hope than Teyla would have expected of people born free of the Wraiths’ shadow.