Mrs. Clay has an eye for a good thing. Her association with the Elliots allows her to live in a much grander style than she herself can afford, and all it costs her is having to pretend the Elliots can do no wrong. There’s also the added bonus of being in prime position to weasel her way into becoming the next Lady Elliot.
While nearly everyone in the novel who sees through Mrs. Clay’s show of friendliness looks down on her, are her actions really all that bad? Sure, she’s making the Elliots believe that she likes them for themselves rather than their cash and position, but they’re pretty eager to believe her. In the end all she’s trying to do is to make a better life for herself, in the only way she knows how – marriage. Those bashing her, however, are mainly concerned that she’s worming her way into higher places than where she belongs, and taking up spots that should be occupied by someone else (Anne, the first Lady Elliot).