While everyone on the internet is used to seeing a lot of bad ads, there are millions of others that never see the light of screens.

Today in its annual report about ads that don't make the cut, Google revealed details of its own "bad ads" battle to showcase the kinds of real and fake promotions the company blocked in 2016.

The volume of ads that violate Google's advertising policies has grown substantially. In fact, last year Google's systems identified and took down 1.7 billion ads across the internet—double what it did in 2015. The way Google puts it, removing that many ads manually would take a human 50 years at a rate of 1 ad per second.

"A free and open web is a vital resource for people and businesses around the world. And ads play a key role in ensuring you have access to accurate, quality information online," Scott Spencer, director of product management for Google's Sustainable Ads unit, wrote in a blog post. "But bad ads can ruin the online experience for everyone. They promote illegal products and unrealistic offers. They can trick people into sharing personal information and infect devices with harmful software. Ultimately, bad ads pose a threat to users, Google's partners, and the sustainability of the open web itself."

Last year, Google updated its guidelines to expand and redefine what types of ads violate its policies, such as by banning payday loan ads, which accounted for 5 million of the ads removed last year. It also made improvements to technology, creating ways to identify "click-to-trick" ads such as those that appear to show a warning on a user's screen. According to Google, 112 million "click-to-trick" ads were removed last year, a totally that was six times as high than it was in 2015.

According to John Brown, Google's head of publisher policy communications, one of the main concerns he hears from publishers is how to grow in a challenging market. However, that doesn't mean they are allowed to post bad ads that others can't. According to Google, nearly 200 publishers were permanently removed from Google's AdSense network between November and December for violating policies about running ads that misrepresent content.

"It's important, especially for Google publishers, and user experience is paramount," Brown said. "Ads are part of user experience, so anything that's misrepresented or not relevant at all to their users, it's a negative to the publisher. And any negative experience can use to them not coming back to that site."

Brown said the company has a team of "thousands" who are tasked with monitoring Google's systems for bad ads.

Here's a look at some of the other "bad ads" Google took down last year:

Ads for illegal products
According to Google, some of the most common "bad ads" the company sees are those promoting illegal products and services. For example, 68 million ads for things that violate healthcare laws (up from 12.5 million in 2015) and 17 million ads for unauthorized gambling.

Misleading ads
Ads that attempt to mislead users with questions about being at risk for things like a "rare skin-eating disease" or miracle pills that help lose a lot of weight with no work accounted for 80 million ads last year.

Ads trying to game the system
Google says some companies that know their ads aren't allowed through detection systems try to game the system. For example, the frequency of "tabloid cloakers"—known by most as fake news—has grown substantially. Many of these ads look like they're going to an absurd and false story of some sort, but then only lead to a weight-loss product or some other promotion.

Last year, Google suspended 1,300 tabloid-cloaking accounts. And while that might not seem like a lot compared to millions in other categories, it actually is—Google said one scan in December revealed 22 cloakers that had shown ads to more than 20 million people in a week.