The Aztecs ruined it for other Indians. Most anti-Indian arguments end up with, "Just look at the Aztecs and their practice of human sacrifice." Without that argument, the Indian haters would have nothing.
A quick recap of Aztec history:
So the Aztecs represent less than 1% of Native time x 5% of Native space. In other words, the Aztecs represent less than 0.05% (1/20th of 1%) of Native history.
To put that into perspective, it would be like understanding US history--the Revolution, the Constitution, westward expansion, commerce, foreign policy, slavery, the Civil War, immigration, etc.--by looking only at California from 2000 to 2001. It's about as close to irrelevant as you can get without being totally irrelevant.
And this doesn't begin to address the reasons for the Aztecs' human sacrifice. For many if not most of them, it was a deeply held religious conviction. I'm not sure we can prove a single Aztec felt an unhealthy lust for blood or a depraved indifference to human life.
For all these reasons, citing the Aztecs in a Native debate is ridiculous. It's like citing one white man who gave an Indian a hand to counteract 500 years of conquest and genocide. It's a joke.
For more on the Aztecs, see The Origin of Yaomachtia and Alternatives to Dark Horse's TUROK.