Anyone investing in SEO services must learn to recognize that difference, says Fishkin. "There are many fantastic people in the SEO field, but there are also dilettantes and outright scammers," he notes.
Formerly, Google's PageRank ratings could be gamed using links placed in comment spam. "Between about 2004 and 2007, people used to be able to leave comments on blogs on other sites with links to their own sites, to build up links quickly," explains Wall.
In response, starting in 2005, Google promoted the "nofollow" attribute for link coding. Nofollow links are excluded when calculating PageRank ratings. Nofollow was subsequently adopted by blogging systems like WordPress and Movable Type for links inserted within comments, cutting off that source of links, Wall says.
Webmasters also used to trade links to mutually boost their PageRank ratings, but now they are supposed to use the nofollow attribute in those links, Wall adds. Consequently, such links are no longer of any benefit. (Advertisements on a page don't get counted as links, as they are typically linked to a click counter.)
Because they are no longer able to use linked comments and traded links, webmasters seeking to maximize their PageRank rating have two options: offer compelling content that other sites (especially blogs) will spontaneously link to -- or pay other sites to link, like J.C. Penney did. The latter is a direct violation of Google's guidelines.
When done by amateurs, paid links are easy to spot, says Fishkin. "When you see a dentist's site with links to student credit card loan sites, you can assume the guy is getting a couple of hundred bucks a month," he says.
In order to get around this, businesses called link farms arrange paid links from established sites with respectable public PageRank ratings, since those links carry more weight.
The most successful link farms don't operate openly. "You just have to know about them," notes Fox. "But often they have been discovered by Google. They continue operating, but their links are not valued by the search engine."
Several reputed link farms were approached for comment but none responded -- except one, whose spokesman said, off the record, that it was an advertising firm and not a link farm, and then hung up. Another announced in a blog that it was getting out of the link business.
Another problem with the link farm business is that it is based on the public PageRank ratings of the linking sites. But Google's Ohye says that public PageRank ratings are actually manipulated by Google to make it harder to game the system. While Google updates the public PageRank database every few months, the public ratings of pages known to be selling links are never updated, rendering their PageRank rating meaningless, she explains.
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