[incosta]

I understand why the author is not willing to share much specifics (such as which free apps get him 4k+ a month in ad revenue) but he still at least could get a number of installs published.

I am skeptical because I know for a fact that some people don't tell the truth. We can only speculate about the reasons..maybe it's to generate more traffic or interest towards the non-free products they offer. I know a fellow (who used to publish a competing product to mine) who boasted online in an article about making quarter million dollars a year after just being a year in business. The same fellow just was trying to sell me his "quarter-million a year business" domain name for 1K a few months before:) In this case, numbers are much more moderate and believable, but still I am not taking this just at the face value, unless there are some facts I can verify, or compare against. The number of active users, for example, and in which countries (mostly) are generating 4K+ /month in ads?