Fabricio you are from Sao Paulo, Brazil - right?
From the things I have heard, I believe that is a more dangerous city than Moscow! I know a woman whose brother got kidnapped in Sao Paulo in the 1980s. Her family paid ransom to the kidnappers, but the brother was never returned, probably killed. I have also heard about people using chauffeured cars in the city because there is such a big risk of being mugged (rich people, probably, but still... )
Of course, it is worrying if random dark skinned people are attacked for no reason in Moscow. Not sure how true that is... but if there IS truth to it, then I wouldn't want to go there if I was black or mixed race. Heard many horrible stories of muggings and shady setups in Russia in the 90s but I THINK such things have stopped now, or are less common.
I once met an African man who had studied in Moscow. He had a good impression of Moscow and did not mention anything about racism.