Why would Elizabeth see Mrs. Clay’s flatteries as superficial? I suspect Sir Walter’s eldest daughter has as good opinion of herself as he does of himself. I think they both believe Mrs. Clay’s flatteries—that is what makes them and her “assiduous pleasing manners” dangerous. The lady seems quite capable of bamboozling them. Look here, neither Sir Walter nor Elizabeth dispute the validity of this flattery although on the whole it is rather silly:

it is only the lot of those who are not obliged to follow any [profession], who can live in a regular way, in the country, choosing their own hours, following their own pursuits, and living on their own property, without the torment of trying for more; it is only their lot, I say, to hold the blessings of health and a good appearance to the utmost…" (3)