helleborine - 1:49 am on Jun 11, 2005 (gmt 0)

Bourbon is nearly over, and I'm ready to roll with a post-hangover analysis.

The phenomena that is most characteristic of Bourbon is stable websites with good rankings making vertiginous drops in the SERPs, sometimes being pushed down a good 20 pages to mingle with sites having the appeal of radioactive waste, combined with an utterly puzzling loss of rank for one's own company name or unique phrases.

What kind of site was affected? Sites medium or small, commercial or homemade, few are safe from this seemingly random application of a penalty to the index page, the page most likely ro carry the PR across the site.

More than a dozen sites with these symptoms were examined. For nearly all of them, off-site content was found that would likely result in the application of a penalty from the fabled duplicate content filter. No one really knows the inner workings of this filter, but it's safe to say that it's not perfect in determining which site is the legitimate proprietor of the content.

Off-site factors that might lead to trouble include rogue URLs, old cache results, and the infamous 302-redirect links. All are liable to trigger this mysterious duplicate content penalty, and carry with them an unknown probability that the search engine will attribute the penalty to the wrong site. We are working at determining this probability, but do not expect results for another month.

What appears to be a faillible application of duplicate content penalties has a devastating effet on the SERPs. For instance, search queries with a company name may be fruitless for a site that has been wrongly penalized by the filter. A small niche may be randomly robbed of its best resource. This is not good at all, and logic dictates that the good folk at the 'plex know this very well. I'm going to go out on a limb here with the wild speculation that the crown jewel that is the duplicate filter has this vulnerability built-in, and perhaps cannot be fixed. If that's the case, the flood gates are wide open for webmasters to knock each other in and out of the SERPs, a state of lawlessness that can't possibly benefit Joe Surfer.

Joe Surfer may not immediately notice a decrease in the quality of the SERPs unless this is brought to his attention by the media or third parties.

On the other side of the coin, the victimized webmasters will suffer from an unexpected, immediate and complete loss of Google traffic. People talk, and desperate people talk more. This makes for very poor public relations.

Google has to weigh whether the duplicate content filter in its current form is worth the damage its brings upon the SERPs, and how its effect on webmasters goes against its celebrated "do no evil" motto. If nothing is done, the damage can only increase as more and more people learn how to use the normally legitimate 302-redirects for nefarious ends, and exploit Google's Achilles' heel to their advantage.