There is a bit of a bug in wordpress. When you copypaste your tab in, it will automatically add or remove newlines, creating ugly ugly text. (In the preformatted font anyway)
To fix:
Go to the “HTML” tab while making/editing the post. If you’ve set it to preformatted, there will be a little thing like this:
<pre>
You need to replace that with:
<pre style=”text-align:justify;white-space:normal;”>
And it should stop ruining your life 😀
Of course this  only happens sometimes.