As Ellen was running away from Espinoza she programmed her clothes to look like the brick wall that was behind her. Espinoza was able to see her because her hair was a different color then the brick wall.
If you want to know if someone is "real" tell them an obvious lie. A human will recognize it for what it is immediately, a cursed will not. They may look real, but they are not. Only real eyes realize real lies.