What do the numbers mean? Do they mean your sites are weak? Do they mean other services do better? Do they mean you did a weak job setting up your sites?
Really, your claim you earned only US$2 on 150 clicks a day (on all 20 sites collectively or on each of the 20 sites?) hangs in the middle of the air. I too have about 20 sites at Noomle. I can report that I get more visits in one day to these 20 sites than I got for an entire month when these 20 sites were sitting in Sedo. At one time I reported to this board about AdSense for Domains. That system got off to a good start for my sites. But has since died down to almost no visits per day. If I move the same sites to almost any other system, the number of visits shoots up.
The original question I was trying to answer was: Which is better, Sedo, AdSense for Domains or a third choice which I have never used? Comparing Sedo, AdSense and Noomle, I see Noomle as the clear winner. That doesn't mean Noomle will make you rich. It doesn't mean Noomle will turn every site into a goldmine. It just means that of the three, one has been better (for me, at least) than the others.