title: what's wrong with e.printStackTrace() for an unknown exception
body: <p>If I use a logger in the case of known exceptions, what's wrong with <code>e.printStackTrace()</code> for an unknown exception ?</p>
  
  <p>I'm always told not to do this - but not given a reason</p>
  
  <p>example below</p>
  
  <pre><code>try {
              dostuff();
          } catch (AException ae) {
              logger.error("ae happened");
          } catch (BException be) {
              logger.error("be happened");
          } catch (CException ce) {
              logger.error("ce happened");
          } catch (Exception e) {
              e.printStackTrace();
          }
  </code></pre>