Yes, I filtered out a couple ads that I thought were low paying as well as a couple that was irrelevant to my site and looking too much like ads. And the next day when it was effective and showing new ads on my site, my CTR went from 3% to above 6% !
I used http://www.adsblacklist.com/ to get a list, and i added some sites that displayed ads i assumed was low thats all