that while John Thorpe occupies the bad-boy role that we find in every Austen novel, he's the only one of the bad boys who isn't even momentarily attractive to the heroine or, at least, to people whose opinions she values. It's not hard/painful for Catherine to figure out that JT is bad news, the way it is for Elizabeth Bennet with Wickham, or Marianne Dashwood with Willoughby. In the other books, rejecting the wrong man after being tempted by him (or, as in Persuasion and MP, after resisting pressure from others to marry him) is part of the heroine's moral journey; in NA, I think, Thorpe is almost purely a comic character rather than an important player in Catherine's moral development.