Why Does Ebay Allow Internal Search Result Pages to be Indexed?

[M_D_Golden_Peak]

Click this Google query: https://www.google.com/search?q=les+paul+studio

Notice how Google has a rich snippet for Ebay saying that it has 229 results for Ebay's internal search result page: http://screencast.com/t/SLpopIvhl69z

Notice how Sam Ash's internal search result page also ranks on page 1 of Google.

I've always followed the best practice of setting internal search result pages to "noindex." Previously, our company's many Magento eCommerce stores had the internal search result pages set to be "index," and Google indexed over 20,000 internal search result URLs for every single site. I advised that we change these to "noindex," and impressions from Search Queries (reported in Google Webmaster Tools) shot up on 7/24 with the Panda update on that date. Traffic didn't necessarily shoot up...but it appeared that Google liked that we got rid of all this thin/duplicate content and ranked us more (deeper than page 1, however).

Even Dr. Pete advises no-indexing internal search results here: http://www.seomoz.org/blog/duplicate-content-in-a-post-panda-world

So, why is Google rewarding Ebay and Sam Ash with page 1 rankings for their internal search result pages? Is it their domain authority that lets them get away with it? Could it be that noindexing internal search result pages is NOT best practice? Is the game different for eCommerce sites?

Very curious what my fellow professionals think.

Thanks,
Dan

[ORob]

Personally, I would test both ways. A lot of SEO value can be found in the long tail, and when someone gets super specific often times they are ready to buy. When I am specific I often find Ebay's search results pages coming up.

For ebay it looks like, your example, these search results act much like a category for a user. If I was looking for Gibson Les Paul, it wouldn't be a bad user experience for me to land on a page full of those guitars. Each item on that page is likely unique and gives me more options. Now if the search was for something different - like a website that only sold unscented white candles, I may not want to land on those results in which case I might go with your other method.

[M_D_Golden_Peak]

I would agree that eBay's search results are like categories (since Google doesn't have a category page for every niche)...and when you combine this with the fact that their "content pages" are auctions that are typically only live for 5-10 days...then it makes sense for eBay.

But SamAsh.com and GuitarCenter.com both set their internal search results pages to be indexed by search engines...and Google is ranking SamAsh.com's internal search page on page 1 of Google in my example above (reference this Google query, and this screenshot). What I notice about their site is that it looks like they are using internal search result pages as category pages. See their Gibson page. The URL structure is the same as if you were to search for something on their site.

So, perhaps SamAsh.com and eBay.com are both treating their search result pages as category pages...since they don't have true category pages for these niches...and thus allowing them to be indexed?

If this is a good strategy, then I'm inclined to think that sites that do have a lot of category pages would want to keep internal search result pages set to "noindex" so as not to duplicate the topics covered in multiple pages. Example: if we have a Watercolor Painting category page...then we wouldn't want a Watercolor internal search result page to be indexed.

Note: None of this even addresses the "lack of unique content" on internal search result pages, which like "Tag" pages on Wordpress sites, I'm of the understanding that this can lead to Panda penalties.

[DoRM]

I am looking into this a lot too.  Our company has 1.2 million pages indexed in Google.  That sounds good except that 1.03 M are from our search results pages.  I am advising we do not keep all the search result pages index; the issues is we are making a lot of money off of them.  What did you find worked best for you? what did you decide to do?