Just when I thought I found the answer to looking up Supplemental result pages within the Google Index, the giant search engine decides to completely remove the notion of “supplemental results” from their index. This doesn’t actually mean that they have removed all supplemental pages, they just removed the “label” of supplemental results from their index, where by giving us as webmasters no indication of whether or not our pages are seen as low quality or not.
Do keep in mind that supplemental results are STILL supplemental, they are just no longer labeled as supplemental. You will still have the negative impact of “never being found” on Google’s SERPs, however there is no way for you to figure out which pages are being affected. Google also made an official announcement on their webmaster central blog which explains why they are doing it, the comments are also interesting to read as you get a glimpse of what other webmasters do with their supplemental results.
Seems the search world is changing dramatically this year and its important for us SEOs to keep up to date with what is happening and how to deal with it. Stay tuned to see what happens next in the weird world of Google.