I have so far not paid much attention to SEO (Search Engine Optimization) for my website: I find greater enjoyment in thinking and writing than in actually being read, and SEO is just a necessary evil along the road. (Just like many engineers would prefer it, if they could fire the entire marketing and sales departments, and hire a few new engineers in order to build more and better products—but find their hands tied by the economic reality.)
However, I have gone to great efforts to “keep a clean slate”, avoid shady practices, deploy HTML that validates and is widely browser conformant, and so on.
As you can imagine, I was not thrilled to discover that I appear to have a “Google penalty”, i.e. a handicap that Google puts on sites that they suspect of being less-than-kosher in their SEO practices.
This is a very tentative estimate, because Google it self keeps quite on such issues; however, the original heuristic claim by one checkere was verified by a seconde. (Then again, web-based checkers are often unreliable.)
After reading up on the topic, the most likely reason seems to be that I link to some sites that could be considered shady, which would draw my own credibility down: I discuss many topics and tend be liberal with linking to sites that could be of interest to the readers—including by serving as negative examples. (Another possibility is that a disproportionate part of my incoming links are from comments on various blogs and newspaper articles, just like comments made using a WordPress account link back to that account. These could be misinterpreted as some kind of comment spam or link exchange—both of which are frowned upon.)
As for my own experiences, I did note a surprising drop (30 %?) in the number of incoming hits from Google in December; however, not one which had me in panic: This could happen e.g. because of an algorithm change or a seasonal variation—and need not be a cause for alarm.
For the time being, I have added a
rel="nofollow" to all external links (which effectively tells search engines that I do not endorse the linked to page). This is obviously unfortunate with the sites that I would actually want to see get more traffic, but I prefer to save more flexible changes until a later date. (I currently use a very basic template language which is transformed directly into HTML. I plan to add an intermediate XML stage in the near future, which will make extensions and alterations much easier.) This in particular as there are some other possible attributes of the HTML anchor-tag that may be useful—and adding them all in the current system would be very messy.
In conclusion: I would recommend others to link with care and to use
rel="nofollow" when linking to sites they suspect of being shady—or simply disagree with: There is no reason why Google should include a “thumbs up” for a site in their algorithms from those who disagree with the site’s message or methods.
However, beware that I am not certain whether I, specifically, have a real problem or just a false alarm—or whether I have the right cure for this particular problem. As a further disclaimer: There is much speculation and little true knowledge of what goes on “under the hood” with Google. Claims in this area should be taken with a greater pinch of salt than statements in more well-researched areas; and SEO is, in my mostly theoretical understanding, partly a game of trying to experimentally find out what currently works, to reap the benefits until the rules change again.