As you pointed out Mrs. Clay (and papa) knows how to manipulate in order to obtain their goals. Sir Walter & Elizabeth are too vain and narrow-minded to see the insincerity in their address but there are pitfalls nevertheless. It takes a bit of cleverness to know exactly what type of flattery is needed to gain a particular point. In Chapter 3 Mr. Sheppard errs in obtaining Sir Walter’s approval of the Crofts when he appeals to him on the basis the former curate at Monkford is a gentleman. As far as I know Mrs. Clay has yet to make such an error. Anne and Lady Russell have no influence at Kellynch; even when they saw her insincerity their efforts to point it out were unsuccessful. Lady Russell (Ch 2.) discouraged Elizabeth’s friendship with Mrs. Clay seeing her as “a clever young woman, who understood the art of pleasing-- the art of pleasing, at least, at Kellynch Hall” and Anne (Ch. 5) warned Elizabeth of Mrs. Clay’s intentions towards their father because she “possessed, in an acute mind and assiduous pleasing manners, infinitely more dangerous attractions than any merely personal might have been.” Acute in Johnson’s dictionary, 1824, page 10 is partly defined as “Ingenious; penetrating.” and “Vigorous; powerful in operation.” Which is not so far from the modern definition of clever—from dictionary.com, “mentally bright; having sharp or quick intelligence; able.” At the moment Mrs. Clay has no reason to fear Anne or Lady Russell because she is subtle enough to fool Sir Walter & Elizabeth. (;D)