Definitions of racism, from the dictionary:
1. The belief that race accounts for differences in human character or ability and that a particular race is superior to others.
2. Discrimination or prejudice based on race.
In other words, if you treat a certain person differently IN ANY WAY based on their race, that is racism (just as lomaid said). Of course your brunette example doesn't work, but Lemonaid's example, in which people thought all asian women were better simply because they are asian, clearly does.
you also missed the first listing..
rac·ism /ˈreɪsɪzəm/ Pronunciation Key - Show Spelled Pronunciation[rey-siz-uhm] Pronunciation Key - Show IPA Pronunciation
–noun 1. a belief or doctrine that inherent differences among the various human races determine cultural or individual achievement, usually involving the idea that one's own race is superior and has the right to rule others.
2. a policy, system of government, etc., based upon or fostering such a doctrine; discrimination.
3. hatred or intolerance of another race or other races
now, in none of my examples did I mention hatred, intolerance or any other form of superiority. .. so none of what was mentioned was racism.. now in 2. it mentions discrimination at the end, so lets look at that..
dis·crim·i·na·tion /dɪˌskrɪməˈneɪʃən/ Pronunciation Key - Show Spelled Pronunciation[di-skrim-uh-ney-shuhn] Pronunciation Key - Show IPA Pronunciation
–noun 1. an act or instance of discriminating.
2. treatment or consideration of, or making a distinction in favor of or against, a person or thing based on the group, class, or category to which that person or thing belongs rather than on individual merit: racial and religious intolerance and discrimination.
3. the power of making fine distinctions; discriminating judgment: She chose the colors with great discrimination.
4. Archaic. something that serves to differentiate.
now, as you can see, what has been mentioned here is a based on descrimination but mostly to light descrimination.. or judgemental behavior. now equating racism and descrimination is a far stretch, but it can happen. thinking only asian women as cute or otherwise is not racism but in fact preference. can this be considered discrimination? Yes it can, it is wrong? It depends.. Prefering Vanilla Ice Cream to chocolate Ice Cream is not so wrong. But other cases can be..
As for the other remarks.. it's no sweat off my back. We all see things in a different light. but to emphatically state that racism - discrimation is like claiming that blue is green.. Sometimes it is, and sometimes it isn't..