Any time Google’s Penguin or Panda updates are mentioned, site owners and bloggers alike work themselves into a mini frenzy about the possibility that their totally legitimate website might have been penalized. It’s warranted, in a way, because a few innocent bystanders have been affected, but largely Google is policing those breaking the rules.
Meanwhile, bloggers have tended to downplay just how much rule breaking there is. Black hat SEO is treated as a fringe issue when in reality it is a huge issue. Writers tend to focus on a small aspect of black hat SEO in which competitors use shady links and other SEO tactics to bring your site down, and that is incredibly rare. Google considers all explicit spam to be black hat, and with that definition, black hat SEO is the most pervasive type of SEO around.
It is also the type of spam Google spends most of their time fighting. Matt Cutts, Google’s webspam team leader, took to YouTube recently to answer a question about how many notifications Google sends out to website owners, and 90% of Google’s manual penalties are still spent on blatant spam pages.
Google sends out hundreds of thousands of notifications each month, but the chances of your common SEO or website owner seeing one are rare. There is a chance though. The other 10% of notifications focus on problems that SEOs who have fallen out of the loop or novices may have gotten sucked up into such as link buying, link selling, or even hacking notifications.