In ye olde days of link building, many sites such as NASA, weather.com and orange.co.uk had indexable search pages of the web that you could inject links into.
Edit: Argos have now made the pages non-indexable 🙂
In ye current days, there are still websites, sometimes major ones that have indexable internal search pages. Generally, it’s not a great idea to have indexable internal search pages, especially ones where you show what the user has typed in. To demonstrate this, we can try and get a Help & FAQ page on Argos.co.uk indexed with “You should not have indexable search pages Argos ~Mark Williams Cook” in the page title.
In this example, we have been kind, but competitors could potentially get rude messages indexed on your site and get you to rank for them. Even worse, there are many of these internal search pages that don’t sanitise their inputs, which means you can do a search with HTML code and get a live link rendered on their internal search page. There are unfortunately, many sites that do this, but I won’t out them for their own protection.
So, by the time of reading this post, you can probably Google “Argos, you should not have indexable search pages” and see what I mean 🙂
Of course, some sites like Indeed.co.uk do this by accident – unless they’re just being honest? 🤔