As a UK born and bred 50 year old guy of Indian decent I would like to give you my view from my own experiences on this issue.
I only started punting 3 years ago. Before that I dated civvies. I dated 2 white girls who stated they would not go with a Chinese guy as they were not attracted to them. But they were not racist against Chinese just wouldn't want to be intimate with them.
As a fair skinned Asian I often get mistaken for Arab, Greek or Italian. So using this to my advantage I have met a couple of girls who claimed they didn't see Asians and they weren't any the wiser. I found them pleasant enough and would not say they were racist.
There is a profile on AW Tiffany Snow who says she only meets white guys as it her preference. But will see coloured guys as part of a duo which I think is a contradiction.
I would also saywhen you categories people by colour you paint a lot of different groups with separate attitudes and cultures with the same brush.
Asian ( North Indians, South Indian, Pakistani, Bangladeshi, Muslim , Hindu, Sikh etc)
Blacks ( Nigerian. Somalian, etc) White ( British , Irish, German ,French etc).
I think you get my point.
I would also say there is a big difference in attitude between Asians born and brought up here and the ones brought up in their own countries. although British Asians growing up in a community exclusively of their own ethnicity tend also to have issues.
I remember talking to a WG girl who couldn't understand why girls won't see coloured guys because of a bad experience. She said she had more problems with white clients.
So my own conclusions is the girls who have a no coloured on their profile are not racist but are sometimes taking the easy way out to avoid issues stereotyped with certain community.