Well if she believes Colonel Brandon (a well respected and honorable socialite and ex soldier), then that suggests that she follows the masses in terms of believing what the most respected people claim. She trusts the general public's decisions/beliefs. Also, since Colonel Brandon had a thing for Marianne, she assumes that he would be a knowledgeable source since he makes it his business to know about Marianne. Her comment regarding Willoughby also reinforces the fact that she holds great store in the gossip passed on by others. She's a comedic character that unconsciously makes nonsensical statements and her behavior is usually inappropriate. Her laughing at her husbands rudeness illustrates this and her lack of understanding of basic