She was easily manipulated in Darth Plageuis.
Sand people are monsters to certain people but tell that to the Sand People and their children. The Children can be seen as innocent at the moment but in time would be killers only through circumstance.. but that is an assumption. Tahira Veila was once a sand person but became a Jedi. Anakin despite avenging his mother, did avenger her with hatred, meaning he was no different. I understand why he did it but it doesnt make it right. Padme knowing this, and at the time, still werent 'dating' means someone can tell you at their first few dates they killed ferets because they were angry. Would you still be with them or think them a little weird?
You mean Palpatine, though I don't recall other then the Valorum thing to be really manipulating but even then with Valorum he wasn't entirely liked by anyone.
As for Tahiri being a Sand Person, she wasn't actually a Sand Person she was a human and even as a Sand Person didn't seem to be really taught anything seeing as she was brought before the jedi at 9 years old, and the fact she had strong animosity towards the cultural aspects of the Sand People.
I would see them as a little weird sure, but its not like Anakin killed a defenseless human being. He killed those who killed others, and raised their children to be savages. Even then though Anakin knew it was wrong for him to do so, being a jedi he shouldn't have given into his anger. So it was wrong being that he was a jedi and he should know better, but it wasn't wrong in the sense that it was a bad thing being that given the history of the Sand People and them killing his mother.