Imagine this pitch: We're going to take your ads and shove them in people's faces. We'll do it so persistently and annoyingly that if users really like our product or service, they will pay just to get rid of the ads. Your ads. Sound good? I'm sure that's not the way Zynga is pitching its mobile ads to advertisers, but that's the way ads on apps often work in practice, and the way a lot of app makers attempt to convert free ad-supported users to paid.You can't blame app makers, game companies, news outlets (including Ad Age) or anyone in the business of making content for wanting dual reve...