Welcome to WebmasterWorld Guest from 188.8.131.52
If you were registered at WebmasterWorld anonymously, then you would be taking no risks in discussing stats here
I see that you are signed up for AdSense on at least one of your sites. And by reading here, you must have an idea on click through rates, and earnings potential
I would guess, like most of us you are testing the waters.
Running similar sites to yours, it looks like good money to me ;)
It's also possible that they don't want to make it too easy for pure entrepreneurs--i.e., people who aren't interested in content or information sites per se--to identify high-profit niches and crank out boilerplate sites to use as AdSense vehicles.