@HowYesNo et al
This problem is much larger than AWS. Look, there are collocation facilities all over the world, cloud hosts, traditional hosting companies, etc. Any one of them can host a bad bot. Over in the
Search Engine Spider and User Agent Identification forum, you'll find an ongoing thread dedicated to Server Farms which is a sort of a catchall term for these types of operations. Here's the forum link.
So, the bottom line is, if you really want to stop this, you're gonna have to educate yourself about this kind of threat. These types of facilities aren't Internet Service Providers (which send real people to your website). They are homes for websites and programs (like spiders and robots and crawlers, oh my) which, at best, have no real bearing on the operations of your website, or, on the darker side, are capable of causing your Adsense account to go into spasms, scraping your content, burning your bandwidth and other server resources and generally messing up your day.
It's a big subject but one thing I've found already is that if you can start by blocking countries that don't fit into your business plan, you'll eliminate large numbers of these Server Farms without ever having to identify them individually. And that's just the tip of the iceberg but it's as good a place as any to good start.