<p>How about a scatter plot with a clear outlier, marked 404. Also this one could be used for captcha, with on the axes speed and reputation and than an outlier with a high speed.</p>

<p>Regrettably, I'm not having time now for a mockup.</p>

<p>EDIT: Drafts by mbq:
<img src="https://i.stack.imgur.com/V5zaO.png" alt="alt text">  </p>

<p><img src="https://i.stack.imgur.com/iOmYq.png" alt="alt text"></p>
