You also get to know when someone looks at your message. shrug From time to time I find this useful. Snapchat claims that the images are purged from their servers after they have been seen. This has come up with law enforcement, I saw an article about it. Right now Snapchat claims that the only images it can deliver to law enforcement, should they be requested, would have to be unopened.
ok, that's interesting now. What if you get a message and it wasn't opened. Say it originated from a known criminal. Postulate further it was sent to a recipient that was intending to open the message. Authorities talk to Snapchat and SC says the message has not been opened and therefore subject to search. If the recipient never opened the message, how can they be implicated?