It’s all about expectations.
Two days ago, I was talking about Susan Boyle with a friend. I do not like her, my friend didn’t even know who she is. I told her about Susan, she has a good voice (not a great one) and she can sing pretty well. The only difference is that she is quite ugly (in Spanish I would say that she is uglier than hitting your own father with a sweaty sock). Her answer was pretty simple: It’s all about expectations.
She said that by looking at her, my expectations were low, so when she sang even with a good-but-not-extraordinary-as-they-want-us-to-believe voice.