I think that a spy novel can easily be a good book. Carre’s books tackle political themes that are important to people, and he uses these to establish more universal themes. A good book, in my opinion, explores human nature.
John le Carré
Why do John le Carre's novels transcend the traditional spy genre? I believe John le Carre's novels, while of the spy genre, transcend it because he deals with universal themes prevalent in major literary works, including poetry. He deals with love, hate, geopolitics, betrayal, hidden agendas, jealousy, and more, while telling complex and emotionally charged stories set against the backdrop of international intrigue.