The Great Gatsby, guessed at his corruption

I'd like to know if, in the following excerpt from the chapter Eight of The Great Gatsby, "guessed at his corruption" means "judged him corrupted" or "lost themselves in conjectures about his corruption":

The lawn and drive had been crowded with the faces of those who guessed at his corruption—and he had stood on those steps, concealing his incorruptible dream, as he waved them goodby.

Thank you.