During the 10/1/2021 John Mueller hangout, one webmaster asked about on-site search results and whether or not they should allow them to be indexed.
John explained that one should use noindex on internal site search results pages. Google wants to be able to recognize these pages, and this could be helped by adding a noindex to the pages.
It’s an ideal situation because the alternative would be a bad user experience—sending people to empty search results pages in Google’s SERPs (search results pages).
This conversation happens at approximately the 37:16 mark in the video.
John Mueller Hangout Transcript
Question related to classified websites. I have ad listings on search results, I allow to crawl and index, I have no ad listings. For some time, should I disallow indexing or should I let Google decide if search results don’t have ad listings, and excluding those pages from the sitemap would also be a good practice?
John (Answer) 37:41
So I think, just just for sake of clarity, I think the search results that this person means are the search results within their own website. So if someone is searching for a specific kind of content, then the website pulls together all the ads that it knows, and it’s those search results, not, not Google search results.
And I…essentially, the direction here is what you should do with empty internal search results pages.
And our preference is essentially to be able to recognize these empty internal search results pages, which could be by just adding no index to those pages. That’s kind of the ideal situation because what we want to avoid is to have a page like that in our index, where it’s basically like saying, “Oh, someone is searching for a blue car of this model and make,” and you have this page on your website.
But it says like, I don’t know of any people selling this kind of a car, then sending people to your website for that kind of a query would be a really bad user experience.
So we will try to recognize those pages and say, like, these are either soft 404, and that we recognize an empty search results page, or you put a no index on them. And you tell us that it’s an empty search results page.
So essentially, that’s kind of the direction to go there. If you can recognize it ahead of time I, we would generally prefer having a no index directly from your side. If you can’t recognize it ahead of time, then using JavaScript to add an index might be an option.
With regards to sitemap or not, the sitemap file only helps us with additional crawling within a website. It doesn’t prevent us from crawling these pages. So removing these pages from the sitemap file would not result in us dropping them from search or would not result in us recognizing that actually, they don’t have any content there.
So removing something in a sitemap file wouldn’t negatively affect the natural crawling and indexing that we do for individual pages.
So I think those are kind of the two aspects. If you can recognize it’s an empty search results page, put a no index on it. Removing it from a sitemap file is not going to remove it from our index.