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.
In this image, we see a young man holding a paint brush and bucket filled with red paint, correcting graffiti on a wall which reads "Enjoy your life." The boy has taken a paintbrush and crossed out the letter "F" so it now reads: "Enjoy your lie.