Antonyms for the phrase "have a good opinion of" include phrases like "have a bad opinion of," "dislike," "distrust," "disapprove of," "hold in contempt," and "look down upon." These opposites of "have a good opinion of" suggest a range of negative feelings toward the person, thing, or idea in question. They imply a lack of trust, skepticism, or outright disdain. In contrast to "having a good opinion of," these antonyms suggest a negative evaluation or perception of something or someone. By using these opposite phrases, it becomes clear that having a positive opinion of something is not always the case, and negative opinions also exist in the world.