The quote by Greville in Dick Francis's book "Straight" reflects the idea that those who engage in negative behavior often look down upon those who uphold moral values. It suggests that people with malicious intentions are quicker to criticize and undermine the actions of those who strive to do good. This adds a layer of complexity to social dynamics, where the 'bad' feel threatened by the 'good' and therefore respond with scorn.

Furthermore, the disdain that the crooked have for the straight implies a sense of superiority they feel in their corruption. It highlights the conflicts that arise between different moral and ethical standings in society, showcasing how negative characters often project their insecurities onto those who remain principled. This tension serves as a commentary on human nature and the challenges faced by those seeking to maintain integrity in a flawed world.