Distortion
Distortion can be a good thing if it is the type of effect you want to use in a special way like on a guitar for that metal grunge sound, or on vocals for some type of loud shouting perception. In mastering, distortion can be accepted in this way as long as it is controlled at a lower level below 0db. The distortion can play well on electric guitars while the other sounds are left alone. This is the case with rock n roll or heavy metal, where distortion is used as an art form.
As it was spoken about before, distortion can result from going over 0db which is what you don't want in a final mastering project. Let the distortion be where it is meant to be, but to completely distort the entire song, I don't think is the usual practice for any artist. On a highly distorted song you just wont be able to hear anything pleasantly or even clearly enough to enjoy it.
At the same time you will most likely pull the plug, or slam the stop button before you get a headache. No artists in their right mind should want their entire song to have a final quality of having distortion so much that no one will listen to you. Put it this way, a song that has been mastered very well with no distortion that sucks will be more tolerated than a song that is great but has been completely distorted.