I surf the Web in Firefox with the Search Status Extension installed. It highlights all rel=nofollow links in a pink color. Whenever I see a site that has all of the internal links with rel=nofollow applied I immediately suspect cloaking.
Here is a screenshot of the Technorati home page:
It seems like all of the links on Technorati.com have rel=nofollow applied, yet it has over 750,000 pages indexed in Google.
My first step in detecting cloaking is to switch my user agent to Googlebot. That is how I discovered that Yahoo is cloaking on del.icio.us. My second step is to view Google’s cache of the page and see if Google has indexed the same page as viewed in the browser.
In both of the above tests Technorati still has rel=nofollow on all of the links. Googlebot is seeing rel=nofollow on every link on Technorati yet is still indexing 3/4 million pages of the site. So it doesn’t look like Technorati is cloaking.
Another interesting test is to view the number of Supplemental Results for Technorati with this query. A huge number of Supplemental Results would be expected on a site that rel=nofollows internal links. I’m not sure how accurate the queries are, but Google is claiming that it has 1,270,000 Supplemental Results for Technorati.com.
Yahoo claims to have 22,807,245 pages of Technorati indexed.
Does Technorati have so many inbound links to so many different pages that it can still get 3/4 million pages indexed by Google?
I have a feeling that this is a case of misguided use of rel=nofollow. Imagine the additional search engine traffic if Technorati started unblocking their internal links.