title: what are the downpoints of this captcha method
body: <p>I use this captcha method on all my forms on many sites, the basic premis is that I have a text box that is hidden by css, if the server-side code determines that there is any content in this box, then the form is not completed.</p>
  
  <p>Client side:</p>
  
  <pre><code>&lt;li id="li-cap"&gt;&lt;label&gt;Leave this field blank&lt;/label&gt;&lt;input type="text" maxlength="30" id="cap" name="cap" /&gt;&lt;/li&gt;
  </code></pre>
  
  <p>Css:</p>
  
  <pre><code>#li-cap{display:none}
  </code></pre>
  
  <p>Server side psuedo code:</p>
  
  <pre><code>if(!nullOrEmpty(input#cap))
  {
      return post back to form with error
  }
  else
  {
      process form
  }
  </code></pre>
  
  <p><strong>this is ignoring any clientside validation for the moment</strong></p>
  
  <p>I've been using this form of captcha (i believe it has a name, can't remember it though, think it begins with p) for a while now, and i'm seeing lots of different kinds of captchas around: mathematical sums, random letters on images, questions.</p>
  
  <p>My version requires no entry from the user, and I get no spam forms at all. Is this actually a good method, or am I just a bit lucky? Should I be using a stronger method?</p>