Since some years Google has rolled out several new policies and search styles. Most of the time we have seen Google fighting against Spams. Having said that it is also quite worse fact that some business development team has triggered the spams in the same space where it is against it and resulting in devaluation of the organic links.
Below is a nice infographic representation of how google devalued the organic links.

Source : SEOBOOK
Below is a nice infographic representation of how google devalued the organic links.
Source : SEOBOOK