Forget the old saying, there is a terrific Willie Dixon song with the above title that's been covered by several artists, including Eric Clapton and The Fabulous Thunderbirds.
Before I go any further, I want to state for the record that I absolutely can't stand TV shows like American Idol and by extension all of it's parents, clones and children. That noted, I find the whole Susan Boyle story at least moderately interesting. If you are not familiar with this, check out the latest on Scotland's finest voice here: Susan Boyle Video.
Just why we, as a species, are seemingly wired to like certain looks while having disdain for others is beyond me. Sure, no one wants to be around someone who, for example, smells, but once you get past basic issues of hygiene, it's pretty clear that there are certain things that society views as "pretty" while certain other things are "ugly". All the more reason why Susan Boyle is an interesting phenomenon. Sure, she has an almost angelic voice, but it's hard to get past the fact that she doesn't look "pretty" per what society seems to value. That makes the whole story that much more interesting: visually many are turned away, only to be drawn back by her voice.
Anyway, in some way Susan Boyle is a hero to anyone and everyone who has spent (all or part of) their lives not being the "pretty" one. Once in a while we need these kinds of reminders.