arutoria - 3:29 am on May 8, 2013 (gmt 0)
Have to agree with what rish3 said.
In some niches that I have been observing, spam has long dominated the SERP, forcing webmasters to adopt shady tactics to "match" the spammers, or they are simply trying to copy other websites' backlink profile. Either way the result is nearly all sites in that niche have shady backlinks.
Then came Penguin and Panda, and the great content got purged.
In a niche that I am currently observing, a big brand site seems to be getting a free pass with thin and repetitive content, while independent sites (used to be on front page) sank, some new spam are coming up.
In the end, "churn and burn" tactics continue to work well while independent sites got purged.