I've heard of people buying a bag with bottles of water in, they quickly swap the bag over after seeing something of worth (like IPad etc).
I don't think I'd buy anything off anyone in the street!
Indeed, more fool you if you don't check the contents.
Thats how they got me, nobody they are pro's at it, the whole thing is one big set up, like the real hustle only low budget!
Uncertainty or not knowing causes depression, Im happy because I know I'm going to die one day!