Google has been trying for a long time to get the Webspam under control. The index should be exempted from Webspam, and the obvious Webspam succeeds Google also quite good. A bigger problem is there are probably clear the so-called content farms. This low quality content that has been generated in most cases only for the search engines is for Google to challenge.
Google is betting that the users more and more involved in fighting the spam, and do so simply by reporting low quality pages to Google. As you can but not only rely, is worked also at the same time still on an automatic detection, achieving low-quality content.
Of course, now speculation for now as it might be possible that Google can recognize these texts. What criteria are based on well-defined? On the one hand, this could be the length of the text, it would be possible, a text that was written to a particular topic, in direct comparison with other assign a certain length, and it must have at least. Short texts could indicate a poor quality. The structuring of the texts and the topic of the text could be measured. It could be also assessed poor text, embed the little pictures or videos.
One of the main themes in the texts is probably the key words. Here, too much use may be wrong, but also a non-use of obvious keywords related to the topic in the context, can indicate a superficial treatment of the whole subject, and thus also to a lower quality.
If you think more about this subject, you will find a lot more points that could be used by Google. So all that is left once again to wait and see what will choose Google.