40% is extremely high. Is your site MFA? If your site provides exceptional content, then you'll have tons of returning visitors, who usually don't click on Adsense. Care to share your secret?
40% . . . I can get that on sites with a couple of impressions a day lol Mine is between 1% - 2% so how you get 40% I don't know. Maybe you just felt like making a thread about crap?