So lets say you take it as a given that snapchat is mostly teens. They look at their snapchats, there is a way to know they have seen them. Lets say you are the GAP and you want to get the latest "look" out there, so you pay SnapChat $.05 every time Snapchat shows a Snap of someone in the "look". Snapchat has to show 50 "Gap" snaps in every 1,000 to make $2.50 per thousand. Typical user will see them on one in 20 'snaps', if the average really is 30 snaps looked at in a day, that is one per day.

I'm not saying you are wrong, what I'm saying is that I can imagine how they would make it profitable should they need to.

Sure, what you're describing is feasible. I was referring only to the idea of end users paying for the Snapchat service.