How can you hold Jaime to a higher standard than Aemon the Dragon knight? Both Aemon and Aegon watched Aegon brutalize, humiliate, and rape Naerys within an inch of her life and did nothing to stop it. Egg did the same to Rhaella.

I don’t. I think the thrust of what GRRM is getting at with Jaime vis-a-vis Barristan Selmy and Ser Arthur Dayne, or Brienne vis-a-vis the Rainbow Knights, or Dunk vs. everyone else, is that being a True Knight is incredibly hard and most people fall short. 

So let’s take Aemon Dragonknight…the great paragon of knighthood, etc. But at the end of the day: Daeron I was murdered on his watch, Baelor I went mad while trying to rescue him, and he died saving Aegon IV of all people from being assassinated by the Toynes for the horrific and largely unjust death of Terrence Toyne. Even leaving aside the whole Naerys/Daeron II question, Aemon had feet of clay.