Google has just added a new section inside the Adsense Panel which is a tool to view detailed diagnostic information about the pages Google crawls to display relevant ads.
Basically, this utility will show you a list of pages where Google has problems crawling content and serving ad pages. It also indicates what might have caused the problems or the reasons these pages are blocked.
See sample screenshot below:
This is a really nice tool you can refer to whenever you see problematic pages or websites showing blank ads or PSAs.
There’s the Google Help Center as well to assist you in solving these problematic pages.