Google announced that they have removed 2.3 billion bad ads in 2018 for violations of both new and existing policies. Google said this included 207,000 ads for ticket resellers, over 531,000 ads for bail bonds and about 58.8 million phishing ads.
That comes out to over six million bad ads per day!
In 2018 they terminated the accounts of one million bad advertiser accounts, which is twice as many as in 2017. They also added 330 detection classifiers to help Google better detect "badness" at the page level in 2018.
You can learn more about what actions Google took on bad ads over here.
Forum discussion at WebmasterWorld.