I agree this seems spurious. There was a mention last week about ads causing pages to scroll directly to the ad slot, this could be the case as it would explain the 100% AVV. I checked my ad networks report and I did not see that network, so it might be specific to your niche. I also never found any of those ads on my sites.

If the ad network is eating up a lot of inventory and not producing revenue then there is not much to loss by blocking it. I would block the network. I have blocked networks in the past that have consistently served spammy ads, but this doesn't happen often.

Thanks for your reply NickMNS.

After running some tests and blocking the network for the entire day, I found out my overall RPM had a huge $0.50 drop and my overall coverage also dropped by around 1.5%. Though, I was then able to go to Allow & block ads and find out what ads had stopped running for the day. To my surprise, the ads that stopped running were all good ads from normal companies with "HIGH" and "MEDIUM" impression scores, but nothing suspicious at all. Also, no Ad Network was listed anywhere under those ads, just as if they came from Google AdWords.

What I'm suspecting is that there is a bug in AdSense where impressions are recorded and generated by that Ad Network, but the clicks are registering elsewhere (maybe through Google AdWords). If so, then that would explain why I'm seeing so many impressions from that Ad Network, but barely any clicks. That could also mean that this Ad Network might be working properly, but a bug is making it seem like it's showing terrible ads (or unclickable ones).

Looking at statistics from previous months, I also noticed that Ad Network was there, but with lower and normal stats and providing a decent $0.32 Impression RPM.

So I enabled the Ad Network again and will be opening a ticket with Google to make them know about the strange situation.

So our first tests mentioned above ended up being inconclusive.

After running more tests, we realized that the Ad Network WAS in fact problematic, using up our impressions for almost zero profit and driving our RPM down. And when talking about stolen impressions, we're talking about millions of impressions here.

We also got a reply from Google in which they said they would investigate the Ad Network in question and also suggested we block it (it's the first time I ever got a reply from Google that suggested blocking an Ad Network. They usually tell you NOT to do so and only do that as a last resort solution).

Something that also caught my attention in Google's reply was when they stated the following: "Google certified ad networks that want to place ads on publisher sites must adhere to AdWords policies. This means they all go through the same quality checks as AdWords ads."

It's a bit frustrating to see that these Ad Networks go through quality checks, but still end up being able to defraud publishers.