Most of the Pop Ups Ads are paying a lot for each view. That's because a pop up ad is visible to every single visitor of your site (except if he/ she use pop up blocker). The deal between using or not is if they will harm the quality of your traffic.
If you join a pop up ads program and use pop ups on your site, your earnings will be much more than if you has a simple PPC program on it. But in my opinion it makes your site look a bit "cheap" and unprofessional.
I believe that no one likes to see a pop up on his/ her screen while browsing a page. Many visitors are leaving the site because of those pop ups, and they might not return back..
What is your opinion? Is it a good idea to use them for a small period of time just to earn a few more dollars?