I can remember being admonished at uni for praising Sidney's sincerity in Astrophil and Stella. 'Sincerity is undemonstrable,' intoned my professor.
One can go too far in the other direction - make authors too knowing, too self-conscious. Hilary Mantel in her otherwise brilliant review of Strangers fashions for us a cynical, detached Brookner, a Brookner who, with an 'authorial snigger', coolly observes the misfortunes of her characters:
We hear the barely suppressed sound of the author laughing up her sleeve ... In this book as elsewhere, she subverts her characters ruthlessly and exposes them to humiliation, not only in the eyes of other characters but the eyes of her reader.
Mantel speaks of Brookner's 'subtle, uncomfortable high comedy'. Comedy? That old thing again. As for sincerity, as for authorial detachment, Brookner's own ambivalent feelings towards her characters (or 'personages', as she calls them), expressed in the early Haffenden interview, are relevant:
Poor little things, I feel sorry for them. They're idiots: there's no other word for them. And I don't know any more than they do.