For traffic from the US, the price per thousand impressions for adult popunder traffic obtained with adspyglass is 1-2 US dollars, but when I try to use HilltopAds, I only get <0.5 US dollars per thousand impressions for traffic from the US. My traffic is a real traffic, I've used other ad network as well, and the price per thousand impressions I get from ADSpyglass is pretty accurate except for the peaks. Now I'm wondering if I should switch to another ad network?