Not too long ago I was working on a site that had a pretty active affiliate program. A very strange thing happened – One of the affiliates unintentionally hijacked the search results of the source site. Let me illustrate what I mean with an example.
The site used to come up very highly in Google for a particular term, let’s call is “discount blue widgets”. The page that Google was listing was “http://www.yourdomain.com”. One day I went back to Google and looked at the current rankings for “discount blue widgets”, and lo and behold, the page listed by Google had changed to “http://www.yourdomain.com?affid=12” (for example).
Now all of a sudden my client was going to have to pay an affiliate commission for all business that resulted from organic Google search engine traffic. Certainly not what anyone intended.
How could this happen? Evidently, the affiliate who was benefiting from this occurrence had a site that was so authoritative that the one link from this affiliate’s home page caused this affiliate’s version of the home page to be seen as more important than the actual home page of the site.
Note that Google sees the http://www.yourdomain.com?affid=12 as a different page than http://www.yourdomain.com, even though the content is clearly identical. In fact, this creates a duplicate content situation, where Google must choose between one version of the page v.s. the other.
So the one link from this affiliate carried more weight in Google than all the other links this client’s site had (the client had not yet gathered many links). Ouch!
So what to do? The fix actually turned out to be quite easy. We added a “rel=nofollow” tag to the link from this affiliate’s site to our client’s site. It took 90 days for it to ripple through to the Google index, but it did, and the problem was solved. By telling Google to not follow the link, it was no longer placing any value on the http://www.yourdomain.com?affid=12 page, so the original home page became the most important version of the content, and got listed again.
When you implement an affiliate program, make sure you retain the right to require your affiliate to add a rel=”nofollow” tag in their links to your site. You should also retain the right to 301 all their links to your site to the page of your choice in the event that they don’t comply with the request to add the nofollow tag. An interesting example of duplicate content and creative uses of the rel=”nofollow” tag.