Disclaimer: I use Disqus ads in my comments section. Yes i despise them, but they actually work great.
I've actually had Disqus ads (those little click bait ads you see on 439274732 'news' sites near the comments section) beating out AdSense on the rare occasion. This usually happens on the weekend, where my traffic is less than half what it is during the week. I was just curious what others have experienced, or if they've not seen anything like that. Furthermore, if Disqus raised their RPM or Google declined to the point where Disqus earned you more, would you pack your bags and make the switch? I've heard Disqus is actually getting into regular display advertising as of late so this actually is becoming more of a relevant question.
For those not familiar with Disqus ads, most are click bait ads that tend to be similar to some spam emails you may get.They are designed to do one thing...to get the highest click rate as possible. They are extremely sketchy and I feel they actually degrade the quality of the site hosting them (even though I use them...that revenue stream...)
Also do be clear, Disqus is probably a long way from killing AdSense. My AdSense monthly figures stomp the Disqus figures and AdSense is what pays the bills. Disqus is usually beer and pizza money.
