You are the perfect example of what people here don't seem to understand. Out of all snapchat users, about 0.5% use it for stuff they want to auto-destruct. None of my friends give a crap about that. You just use it to send pictures that aren't worth saturating your phone memory with. Dumb stuff, or funny stuff. One of the last pictures I sent (before those a*sholes blocked me) was a potatoe I had found that looked like a nazi cross. It was funny, but not worth taking a "real" Picture of; It had nothing to do with "trusting" my friend of telling everyone I had seen a nazi potatoe.
You are also forgetting the "my story" part, which is like any social network status update.
I'm just attempting to explain the REAL use of snapchat, but i perfectely respect your opinions