I think it is really easy to spot a foreigner in Moscow, not (of course) with hair and skin colour but everything from their clothes, attitude and their language skills. Here are the ones that I have spotted so far:
The Majesties: They are the top of the cream. They have either came here in 1990 and prospered in the post-soviet mayhem or are imported CEOs of the new chic Russian firms. They are strongly shielded by their guards or supermodel girlfriends, ride in the custom built limousines and live in the suburbs of the city, away from the dirty Russian crowds and muddy streets. They either speak Russian fluently or hire someone to do so. They can be seen in Millionaire Fairs or ultra-top-secret parties.
The Achievers: They are the senior expats that came here for a limited amount of time and never care to learn about the culture and language. They usually live with their families and strive to find a decent school for their kids, away from bacteria infested russian school kids (actually one of those guys really told me that). They hang out in expat bars and usually buy out their company (instead of dancing, flirting...etc). The ones with ferocious wifes prefer classical music concerts and a dinner with family in good restaurants. They ussually drive the company cars and make a lot of accidents. They can be seen in Novy Arbat, buying overpriced souvenirs and fake soviet memorabilia.
The Newcomers: They are the junior expats that have somehow started their international career in Moscow. They are overenthusiastic about learning the culture and language; but quit after realising that it is not a piece of cake. All they end up learning is asking the price of bread or describing the way home to taxi drivers (they do it in a heavy accent to get a spicy fare). They are usually good-looking men but have a priority to save some money in the most expensive city on Earth, so they use their passports, bad accents and european drinking habits to flirt with Russian girls. They can be seen trying to drink vodka shots in expat bars, trying to dance in dancing clubs and trying to make shopping in a russian supermarket. Unfortunately they are sent to another country (or back home) when that "trying" phase is over. They usually use the metro (you can spot them looking blankly on the metro art and decorations)
The Caucasians: They are the people from the Caucasus (Georgia, Azerbaijan, Armenia...etc) Actually they are not foreigners (many living in Moscow for generations) and speak Russian fluently; but have created a getto culture and outfit (similar to the african-americans). (Sharp-tip black shoes, tight blue jeans, shiny black leather jacket with greasy black hair) They can be spotted in old and rusty Lada's and Volga's in search for a customer.
The Turkish: They are the absolute masters of the non-slavic league in Moscow. A lot of them came as slaves to construction business in 1990s but made their way up in various ways. The top achievers have already blended their lifestyle into russian and created families; but a lot of them are just present for the fun and the girls. The most important thing is that they can be seen anywhere, doing anything (from expensive french restaurants to low profile vodka halls). The difference between the other foreigners and the Turkish is that the Turks are offended by the reality that he is not the only Turk in Moscow . (There is no national fraternity whatsoever) They never prefer to socialize with each other (although the English are the most intra-social group; they gather and don't care about the girls but the prices of lager beer instead)
More foreigners descriptions coming soon..