While Becky thinks she’s clever, Miss Crawley can immediately see through this trick, showing how Becky’s vanity sometimes leads her to underestimate the intelligence of people around her. Rawdon himself, while gifted at gambling schemes, can also be oblivious sometimes, not understanding that he should do as much as possible to win over Miss Crawley. This obliviousness is not necessarily a character flaw, since it could suggest he’s less interested in manipulating people than Becky.