If a link exists, and nobody clicks on it, could it still be valuable for SEO? Are they still valuable? Should an SEO seek to earn more links like those, even though they don't earn referral traffic?

Yes, the link has value for merely existing. That value is determined by the SEO metrics of the page and domain of the site offering the link.

I wouldn't focus on obtaining more links without referrer traffic per se. My focus is obtaining quality links, which usually means they are visible and will receive traffic. If I was offered a link on a site with good DA and PA that would never get clicked, would I take it? Yes. It will help my site rank higher which can lead to more organic traffic from search even if the link itself did not offer any traffic. It's the reality of how the system works.

This process is why many black hat SEOs grab links from dead blog pages, asian sites, or try to stuff links into

<noscript>and other unseen tags.</p> <p><strong>Does Google take referral data into account in evaluating links?</strong></p> <p>Google reveals as little as possible about their algorithm other then to say they list over 200 metrics and constantly adjust their metrics.</p> <p>Those are the facts involved with your question. If I was to speculate, I would think Google either has determined, or will decide, that a link with zero referrer traffic should be devalued. The challenge as always is obtaining clean data that cannot easily be manipulated.</p> <p>PS. Love the attachments :)</p></noscript>

The preferred option would be the noindex, follow tag.

The robots.txt file is a choice of last resort. The best robots.txt file for a site is an empty file (i.e. no disallows). The robots.txt file is a tool that can be used when other options are either not available, or the effort is deemed as too great.

If you use robots.txt and the url removal from google, that will work, the page will get de-indexed, but then Google will never crawl that page again and therefore not follow any of the links on that page. You are blocking their crawler so your site will not be crawled as thoroughly which means pages can be missed, a lower pecentage of your pages will be indexed (mainly applies to larger sites), and the link juice which flows to any of the blocked pages will lose their value. Any anchor text or other link value on those pages will be lost as well.

If you use the "noindex, follow" tag then those pages will still be crawled, those pages will continue to contribute value to your site and the page's links will continue to offer value to their target URLs, many of which will be your site's internal pages.

A final point is the URL removal tool in Google WMT will remove the page from Google, but it wont affect Yahoo, Bing and other directories.

What do you mean "uk.com" is not a proper TLD? There is nothing wrong with it. Your TLD does not affect your site being indexed.

Can you offer more specifics on the problem? Take one page and explain, in detail, how the search results are not matching your expectations.

Please provide the URL and the term you are searching for, along with the search engine used (i..e Bing? Google UK? etc)

apparently I was quick enough to answer it twice before you could answer once

I tried to delete the 2nd post but I get a site error. C'est la vie!

If I  update any links, this will make said link new to Google, so if link age is a factor, would this also lessen the value passed initially?

My answer to you is NO. But you should be aware there is at least some dispute on the topic.

The SEOmoz point of view (which I agree with): http://www.seomoz.org/blog/age-of-site-and-old-links-whiteboard-friday

Another point of view: http://www.the-system.org/2011/01/google-algorithm-change-attacks-spam-or-does-it/

If I  update any links, this will make said link new to Google, so if link age is a factor, would this also lessen the value passed initially?

My answer to you is NO. But you should be aware there is at least some dispute on the topic.

The SEOmoz point of view (which I agree with): http://www.seomoz.org/blog/age-of-site-and-old-links-whiteboard-friday

Another point of view: http://www.the-system.org/2011/01/google-algorithm-change-attacks-spam-or-does-it/

This is the challenge about replying to "fast" questions in a Q&A. How thorough of an answer should be provided. I agree with EGOL in that the category and tag pages could and perhaps even should ideally be built out, offer more content and be indexed. Many sites choose not to take this approach and simply keep these pages merely as indexes or organizers. IF you choose to do such, then I maintain my original advice to use the noindex, follow tag.

With respect to robots.txt, the best file is a blank one. Many sites use the robots.txt far too much. It should be avoided whenever there is another solution available. In this case, it would be a big mistake to use it.

I agree with John.

You do NOT want to have "no index, no follow" tags on internal links. "noindex" is fine, but "nofollow" is an indication that you do not trust the link. It sends mixed signals to search engines and is not a good idea.

If your category and tag pages have no content and merely contain links to other internal pages, then "Noindex, follow" is the tag you want to use.

An alternative approach, as John mentioned, is to build out those category/tag pages with more content so they offer value to searchers.