Last December, Adsense introduced a Brand Saftey procedure. This caused a significant drop in earning for lot of publishers, especially those with low traffic, or with lot of pages, which themselves are receiving low traffic.
This is understandable why Adsense is doing this, to keep its advertisers, which no longer want to appear everywhere without a minimum of control of the content of the page on which their brand is showing.
I know that Adsense might not mind, but may be we can shuffle ideas on how things can be improved and be mutually profitable for both advertisers and publishers.
Personally, I wish Adsense would be able to use Google search/Googlebot data. I know Google Search and Adsense are separate entities, but still. Obviously, the Adsense bot does not have the resources to crawl pages at large scale, which is why it takes a while before ads start showing on a new page, or pages which have not been visited since some times. So if Adsense was able to access Googlebot (search) crawl data, it might help speed up things, and may be also be more accurate.