What you can’t see, can hurt you.

So-called bad actors (organized criminals that profit from traffic fraud) are deliberately hiding ad slots on web pages. It’s bad for business, as advertisers end up paying for ad space that have little chance of ever being seen.

The reason they’re rarely seen is because, sometimes, the fraudulent supplier will stack multiple ads inside a single slot (and only the top ad is actually visible). And in other cases, they create a small ad-serving iframe that’s nearly impossible for users to view.

Google, for one, says it isn’t blind to this issue of hidden ads. So today it launched a new feature in its DoubleClick Bid Manager that essentially blacklists suppliers that try to sell hidden ad slots.

Since purchasing anti-ad fraud company spider.io, the technology company has been working on the new system that essentially filters through a list of ad suppliers, and weeds out the dirty players whose goal is to sell useless inventory.

Those bad actors are then completely removed from the exchange before advertisers have a chance to bid on them. Currently, Google and spider.io blacklists 2.6% of the inventory accessed by DoubleClick Bid Manager across exchanges.  However, it says this percentage varies widely depending on the provider.

“Ad fraud is perpetrated by organized groups that constantly change tactics to defraud the industry for their own gains,” says a Google/spider.io blog post on the new service. “That’s why we’re always researching and updating our defenses to ensure advertisers are getting the media they intend to purchase.”

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