<p>I would be in favor of <strong>option 2</strong>.  The existence of 46 (as of 9/16/2014) tagged threads suggests that the tag has some organic utility for organizing the topics within CV.  </p>

<p>However, I would make two suggestions:  </p>

<ol>
<li>Don't re-tag all the candidate threads at once, so as not to spam the main page.  It is best, IMO, to do a handful at a time.  As a further extension of that idea, it is best to do the re-tagging during slower traffic periods.  </li>
<li>I suspect part of the problem is that <a href="https://stats.stackexchange.com/questions/tagged/kernel-trick" class="post-tag" title="show questions tagged &#39;kernel-trick&#39;" rel="tag">kernel-trick</a> has no tag wiki excerpt, and the excerpt for <a href="https://stats.stackexchange.com/questions/tagged/kernel" class="post-tag" title="show questions tagged &#39;kernel&#39;" rel="tag">kernel</a> is too sparse.  The excerpt for <a href="https://stats.stackexchange.com/questions/tagged/kernel" class="post-tag" title="show questions tagged &#39;kernel&#39;" rel="tag">kernel</a> could be clarified a little, and something like 'DO NOT USE this tag for [kernel-trick]' could be appended to the end.  Likewise, a suitable excerpt for <a href="https://stats.stackexchange.com/questions/tagged/kernel-trick" class="post-tag" title="show questions tagged &#39;kernel-trick&#39;" rel="tag">kernel-trick</a> should be created.  </li>
</ol>
