Why Google is Broken - State of Digital ∞
"After Caffeine , the SERPs were inundated with results of dubious quality. Google, therefore, tried to correct this with a series of updates.
The first was Panda (and just before it the ” Scraper update”). Thanks to it the SERPs were cleaned of documents with thin content, which did not offer real value to users and whose sole purpose was to rank for the largest number of keywords. (Do you remember Demand Media and EHow?)
The quality improved, but not that much. Those documents, in fact, were mostly replaced by those that based their strength on manipulative link building tactics.
For this reason Google introduced Penguin.
And, in case that Penguin alone was not able to definitively eradicate the effects of link spam, Google has dramatically increased the number of manual penalties and actions against everything that Google tends to be defined as a link network (hence guest blogging platforms too).
With the SERPs “cleaned” of thin and poor value search results (Panda ) and the result of link spam results (Penguin), the quality has improved … but not that much.
As in a nightmare without an end, their place wasn’t taken by immaculate and highly valuable web documents. No, for the most part we began to see how the good old exact match domains sites conquered the SERPs.”