Vaemond might have been an excellent knight and Lord of Tides. But he must have been lacking in the IQ department for he dared to insult Rhaenyra and her sons openly in court.
In the “strong boys” fight, Aemond only gets on the defense when Daemon steps in between him and the boys. The two men are the driving forces of their respective sides.
Almost everyone made a toast in King Viserys’ presence. But, Aemond makes one after the King leaves. He calls the Velaryon brother “strong boys”, once again calling them bastards.
Even in his last breaths, he was thinking of his daughter and his true love, his first wife Aemma. Viserys’s death signals the end of peace in the Seven Kingdoms.