They were two of Shay's old friends who'd run away to the Smoke the time she'd chickened out, so it must have been months since they'd seen a pretty face. Everyone seemed willing to let her go on complaining. (47.38)
Compare Croy, Astrix, and Ryde's reaction to Shay ("she has big eyes, so we have to listen to her") to David's reaction: "It was as if David didn't see her beauty"(47.57). This isn't a scientific experiment, but his reaction does make"prettiness" seem cultural. If it were biological, David would be into Shay; but he's not. So, Shay proves her point about how being pretty isn't so special—but she only proves it when she gets made pretty. Darn irony.