Google runs one of the biggest online ad networks in the world. There’s a good chance that almost every website you visit has ad banners that Google operates. Being really popular means scammers will target will constantly target it to make many quick bucks. Google responds to this illicit behaviour by banning ads. In 2016, the company took down nearly 1.7 billion ads that violated their policies, which is twice as many ads it took down the year before.
There are many ways in which scammers try and deceive the unsuspecting Internet user. One of the popular ways is by loading malware by showing fake system warnings (dubbed “trick to click”), leading the user to believe their computing devices are affected and that clicking it will fix the problem (when there was no problem to begin with). Google developed systems that would spot these malicious ads, and in 2016 detected and disabled 112 million of them, a 6x increase from the past year.
Next, the search giant also cracked down on ads that promote illegal activities or products. For instance, 17 million gambling ads that did not have the proper authorisation were taken down, and 68 million healthcare related ads that were not legitimate were pulled down too.
There are also scams that go by the name of ‘tabloid cloakers’. You’ll typically see what looks like a clickbaity news story, but instead of landing on a news portal, you’ll end up landing on a site that sells products, say for weight-loss. Google took down 1,300 accounts responsible for publishing these ads. The company also went the whole nine yards on sites that were promoting 'payday loans', suspending 8000 websites from the Internet, over and above banning 5 million payday loan ads on their platform.
Last but not the least, the company also tightened its stance on the rise of fake news on the Internet, by introducing a new AdSense misrepresentative content policy. After reviewing over 500 websites that were suspected of misinforming its audience, with some of them even impersonating as news organisations, action was taken against 340 of them and 200 publishers were permanently kicked out of Google's ad network.
You can read more about these actions on its blog.
Google makes a majority of their revenue using ads, so it’s in their best interest to keep malicious ones from creeping into their system, and lose customer faith. Beyond this, they’re also working with publishers to make ads that aren’t as obtrusive.