In addition to her ME1 conversations about not wanting to trust or be dependent on the other races to solve a human problem, pretty much every mission I took her on in ME3 brought out some snide comment about aliens - either not handling their own problems or using Shepard to solve theirs. I think she's a racist, reforming as she has more contact with aliens.
The only example of that I can think of off the top of my head is the Ardat-Yakshi monastary. She says something like "The asari owe us big-time for this" Amusingly enough, Liara (who I also brought on the mission) chimed in with "Agreed"
Help me out here, is there ever a moment in the game where she does something for, or says something positive about aliens on her own, besides helping Shepard save the galaxy? A few come to mind:
- ME1: took the position that the Council should be saved in one of my ME1 playthroughs
- ME3: thinks of Tali as a sister
- ME1: thinks the Prothean ruins that Liara was trapped in were impressive
- ME3: tries to save the Council, and with influence puts a gun on Udina, and might even shoot him
Ash doesn't trust groups. She trusts individual people. She's not mistrustful of aliens because of their biology or some sense of natural superiority of humans, but that since they are beholden to foreign governments, they may not have the best interests of humanity in mind. Notice the (often conveniently overlooked) attitude she holds towards bureacrats, politicians, and corporate types: people who are traditionally viewed as self-serving. One of her more amusing lines to me in ME1 is when she comments on how "It sucks to be a patriot and p*ssed at the government. Who am I supposed to vote for?"
She is cynical and mistrusting. But when a person proves themselves in her eyes, she'll have their back, regardless of race. Look at how willing she was to work alongside the STG.