"I would not be so fastidious as you are," cried Bingley, "for a kingdom! Upon my honour, I never met with so many pleasant girls in my life as I have this evening; and there are several of them you see uncommonly pretty." (Chapter 3)

At first I thought Darcy’s fastidiousness was only about ladies who were not handsome enough but I think the description actually implies more than that. When Bingley chastises Darcy for his fastidiousness he is saying something not so complimentary about his friend’s character, from Samuel Johnson’s Dictionary, A Modern Selection by E.L. McAdam and George Milne:

Fastidious. Disdainful; squeamish; delicate to vice; insolently *nice.

Darcy’s fastidious nature is not understood or seen as necessary by his friend Bingley—who is I think the last person, save Jane perhaps, to say something so uncomplimentary of Darcy if he did not think it was true. Darcy behavior throughout the assembly illustrates this definition very well, but especially so when he explains why Lizzy is not good enough for him to dance with. I think Bingley is showing a perceptive insight into his friend’s character. :D

* I believe nice is being used as defined by Henry Tilney in NA, Chapter 14: “Originally perhaps it was applied only to express neatness, propriety, delicacy, or refinement — people were nice in their dress, in their sentiments, or their choice.” (Please, NA responses should go to that board--I do not wish to start cross-novel discussion!) :D