Art, you should probably refrain from drawing conclusions and calling people liars without understanding the factors that affect ad revenue. As thewitt has alluded to, the number of people who install an app is meaningless; what's important is the number of impressions and the number of clicks. Your app could have an install-base of hundreds of millions but if users are never running it, you will never see ad revenue. In order to see that, you need to have engaged users: ones who will run the app for good periods of time and will click on ads they're interested in.
I'll give you a bit of a peek into my personal experience. One of my apps, a.k.a., which is ad-supported, has had over 65,000 impressions via iAds so far this month. I'm seeing a click-through-rate of 0.21% and my revenue so far is $22.07. On top of this I am also serving AdMob ads, so there's additional impressions, clicks, and revenue that I have to consider. Hope this helps.