How we cite our quotes: (Volume.Chapter.Paragraph)
Quote #1
He was of the highest degree of middle stature. (1.8.4)
What's the highest degree of middle stature? Sounds like Joseph's the most average of the average. Nothing really stands out about him, though he's got a pleasing face. But you could also read it this way: Joseph may only be of average height, but because he's so cute, he still seems like the exemplar of average height. Nobody does average height better than he does.
Quote #2
His hair was a nut-brown colour, and was displayed in wanton ringlets down his back. (1.8.4)
Sounds like Shirley Temple to us, but seriously, Joseph's "wanton ringlets" suggest that while he's careless about his appearance, he's still awfully attractive to the lady-folk.
Quote #3
Leonora was […] tall and well-shaped, with a sprightliness in her countenance, which often attracts beyond more regular features joined with an inspid air […]. (2.4.1)
Leonora's spirit is the most attractive thing about her. (Maybe it's the same spirit that prompts her to throw away Horatio.) Joseph is similar: sure, he's hot, but what makes him extra hot is that he's not really aware of how hot he is.