Just got done with this pretty good book on marketing called "Selling the Invisible" by Beckwith.
Most important thing I got out of it was the points you need to cover to have a complete value proposition to any potential customer; you usually need to cover all points to get people to take their wallets out:
We are (who are you?), and we do (what do you do?) for (who cares what you do? who do you serve?) who need (what special needs do those you serve have that they can't take care of without you?). Unlike our competitors (who are they?), we're different in this way (how so?) and that's important and people care about that because (what's the unique benefit to your difference?).
Pretty simple, but how many startups you think can fill in all those blanks? I'd be willing to bet next week's beer money most people never think it through, from a marketing perspective, past the "who are we" part ... maybe the "what we do" part.
But often the answers to these questions are found (or changed) by experimentation. The point of a scrappy startup tends to be that experimentation, not a sophisticated execution of a great idea.
I've read your comments, and while I appreciate your economics perspective, and I do agree that's immature to pretend to be a sophisticated business when really what's being built is a sloppy experiment, it's not going to be well received to attack the focus of this community: experimentation.