Kortney said:
Distrusting the opposite race for no logical, valid reason=racist. It's a fine line.
There is a logical and perfectly valid reason though. The main reason Ashley distrusts alien is because she imagines that, when push comes to shove every race will look out for the interests of their own over others. She argues not to mistreat aliens or turn them down as allies but not to also expect aliens to help out in a crisis and instead should be prepared and capable to do things like this on their own.
If you ask me it's a very logical way to look at things. After all the Council have a history of letting problems go on outside of their territory for long perios of time, only stepping in when it endangers them. Quarians have a history of being largely self serving and being too busy with their own problems to bother with the problems of others. Krogans have the reputation of jsut being violent with no interest in helping so much as causing more problems.
Batarians and Geth are isolationists.
It makes sense to argue that these races might not rush to the aid of humans in the event of a disaster, especially not if that same disaster also effects them (the alien race in question).
Think about it, if a giant earthquake caused disaster to both Australia and China, who do you think the Chinese government would be more interested in helping out?
As for Ashley?
This is a mindset that comes from her family name being ground through the dirt due to her granfather being the only human ever to surrender to an alien race. She's had to fight to get where she is and does everything she can to rank up but is held down by the bad family history and subsequently lack of personal experience. Hence she's reverted to the three basic principles that can apply to meeting new cultures:
1. They will look out for their own before us.
2. They didn't get to the apex of their glory by being friendly. Wimps do not become top dogs.
3. They will assume the same rules apply to us.
Also in regards to all this, Ashley says and does numerous things to contradict the idea of her being racist, for instance she never idealizes humans as being superior to aliens, she never argues that aliens are lesser beings.
On Virmire she has no complaint working with the Salarian team and even volunteers for the job. She also hopes for improved relations between Humans and Quarians thanks to Tali helping with Saren. She also despises groups like Terra Firma and will vocalize strongly against them. Also despite showing hostility to Liara, she still notably shows sympathy towards her in regards to the death of her mother (hinting to Shepard to go talk to Liara because 'it's gotta hurt').
Point is, Ashley never had the true irrational bloodied hatred that everyone seems to think she has. It all comes down to practical concerns.