I tend to think of the answer as appropriate if:  

 1. It's evident that the user is after a specific way of doing something, but the goal can be accomplished in another way  
 2. It's appears that the question is a bug complaint, but there is a known work-around
 3. **Don't do it** answers are, I think, occasionally appropriate.  Most often more appropriate as comments, but I think sometimes and answer of "Bad idea" is appropriate

[Here's][1] a simple example.  It's evident that the OP wants a CSS based solution.  A CSS solution might break if the theme was changed, so I suggested an alternate way of doing what was needed.
  
[1]: http://askubuntu.com/questions/180258/how-to-add-some-margin-for-icon-space-in-unity-bar-menu/