Google indicates that a change is a response to numerous complaints of Internet users annoying when sometimes when you click a link in the search difficult for them to find the right content. And they came to the assumption that "what we are looking, it should be visible at once, and not on the bottom of the page, for example, the entire mass advertising."
While Google says they won't provide any official tool that tells you how many ads are too many, they do recommend using the Google Browser Size Tool to see how much of a page's content versus ads are visible to users of various screen resolutions.
In this way, the Mountain View company indirectly in this way encourages publishers (website owners) to place AdSense ads at home. Please note that Google will not take into account: pop-ups, pop-unders and ad overlay that can easily turn off. Google just cares about what is in the upper parts of the website header, since some time displays these areas at home as a preview on the search results. This change aims to tackle overloaded web pages ads, and I think this change will be beneficial for the typical internet user.
Afraid your website will be affected? Google stresses that this new change will affect less than 1% of global queries or less than 1 in 100 searches. So, yes you could be on black list, especially if you or your client exaggerates with earning in this way.