Reassuring to know they are being proactive. This is one of my pet hates which I invariably end up fixing for friends and rellos:

Unwanted software
Unwanted software can slow your devices down or unexpectedly change your homepage and keep you from changing it back. With powerful new protections, we disabled more than 10,000 sites offering unwanted software, and reduced unwanted downloads via Google ads by more than 99 percent.

Another giant scam - which I still see all day, every day:

Trick to click
We got even tougher on ads that mislead or trick people into interacting with them—like ads designed to look like system warnings from your computer. In 2015 alone we rejected more than 17 million.

They might have got tougher, but they are still there - perhaps from different ad networks though. I must check a few out.

This is more of the malvertising threat which has been on going for years (and partly to blame for the rise in ad blockers)

An outsider look at g's activities:

Google blocked 780 million malicious and annoying advertisements last year, up from 256 million in 2014.

The company says it has destroyed more than 10,000 sites foisting software like download wrappers, which install adware and the like. This, it says, reduced the total unwanted downloads through Google ads by 99 percent.

[theregister.co.uk...]
Is this too little too late to stop of spread of ad blockers? Time will tell.

Another giant scam - which I still see all day, every day:

Trick to click
We got even tougher on ads that mislead or trick people into interacting with them—like ads designed to look like system warnings from your computer. In 2015 alone we rejected more than 17 million.

I wonder if that includes the "download now" ads you see on pages for software that you're actually interested in downloading, that's easier to get tricked by than "system warnings."