<p>Yes, but only for a very short moment. I agree that it <em>may</em> indicate sloppiness, but in general I agree with the fictional Prof. Smith</p>

<p><img src="https://i.stack.imgur.com/UX5VI.gif" alt="enter image description here"></p>

<p>(source: <a href="http://www.phdcomics.com/comics/archive.php?comicid=1399" rel="nofollow noreferrer">PHD Comics</a>)</p>

<p>The only harm the user[0-9]{1,n} causes is, that I will not remember him because I am not able to recognize him in different threads. To me, all these names are the same. But that's it.</p>
