of how Darcy acts than what he says. It is said that he constantly looks at Elizabeth, to me it sounded that he even stared quite a bit. And E. herself thinks something like "that kind of a man can't admire me" (sorry, I'm at work and haven't the book) and "he looks at me because there is somathing wrong with me". So she notices it but draws wrong conclusions of it. It is very true that Darcy doesn't say anything to make the matter plain.