Follow the MONEY. Oh wait. Can't do that.
If the google were sincere then the most obvious thing they could do would be to offer to display the developers' financial models. I'm not saying they have to forcibly expose the money, but they should give the honest developers an option to explain where the money is coming from, and where possible, they should explain why they think it's true or false. Imagine a "Financial Model" tab with the developer's explanation of the money at the top, and the google's uneditable reaction at the bottom. This would let us make meaningful and informed decisions about the apps in most cases.
In most cases, the developers would be able to select from a relatively small number of standard models. For example, if the developer says it's ad-supported, then the google can say whether or not they have actually been paying money to the developer without giving out exact numbers. Maybe the developer claims to be independently wealthy, but all the google can say is "We don't know." That's still useful in deciding if you want to download the app. Perhaps the financial model is "Produced for a class project", then at least we will know not to count on long-term support if the app seems likely to need any.
All in all, I've lost almost all of my respect for the google. I think they are EVIL now, and the real motto of today's google is "All of your attentions is belonging to us."