I am a foreigner but you asked interesting questions, so I'll make some observations:

Quote Originally Posted by Johanna

--Is the situation different in countries like Ukraine, Belarus, Kazakhstan?
I met some people from Kazahkstan, they spoke Russian very well... but they looked Russian to me, so well - ok why did I even write this?

Quote Originally Posted by Johanna
--Do you know any foreigners who have learnt Russian and can speak it well?
Russian is a very difficult language I think for most foreigners... I'd place it as a 3.5/5 or perhaps even 4/5 on the difficulty scale of European languages. One thing Russian has going for it is that the language is quite clear... the speech isn't sloppy like say Polish or French (at least those languages sound sloppy to my ears) or utterly alien and mystifying like Hungarian. So at least (with some exposure), you should be able to at least pick out the words - even if you have no idea what they mean.

Quote Originally Posted by Johanna
--Can Baltic people usually speak good Russian or not? I have noticed that they always mention "native fluency in Russian" on their CV/Resume.
Well ethnic Russians there certainly seem to but also I met some Latvian Latvians and they seem to speak Russian much better than most other foreigners I've met - but not as good as the Russian Latvians. At least from my experience. My understanding is that Latvia is still about 40% native (but treated like 2nd class citizens by the government) Russians, even with all the post Soviet emigration. But I could be mistaken, maybe the 40% figure is high now?

Quote Originally Posted by Johanna
--What about the Central Asian people who work in Russia - what are their Russian skills generally like?
Uzbeks (I'm guessing they are uzbeks since they sell the uzbek tasty bread), sound absolutely horrible... much worse than Arabs.

Quote Originally Posted by Johanna
--What about Westerners - how often do you meet somebody who can actually speak Russian well?
It is rare, especially if that Westerner is American. Many Americans living in Russia/Ukraine either have no interest in learning Russian, or if they do - it does not come to them easily (e.g. after 3 years of living, the -better- ones are just being able to hold conversation - even having had tutors for at least a year and being immersed for 3+ years - and still have absolutely horrible accents).

I'm sure there are some Americans that speak it well and with softer Accents but really the only ones I personally met that spoke it well were in the military. Americans have great difficulty even just pronouncing the language. They (as a rule) usually cannot seem to pronounce 2 consonants together (which is a common feature of Russian) nor can they do a rolling 'r'

There are some westerners that can converse "proficiently", but they still have quite noticeable accents usually.

There are 2 caveats to what I wrote... 1) I don't come in contact with too many foreigners living for a long time in Russia on Business and 2) same goes for students from Western countries... so I don't know about these groups, I suspect there must be some among them that can speak Russian quite well.

I did meet an Englishman who I was impressed by. He never studied it, merely lived in Ukraine a while and is married to a Russian speaker. But his is merely functional Russian, he was able to get his car fixed in front of me (explain the problem to a taxi driver, get taxi drive to drive him to mechanic, get mechanic to fix the problem) without any help from me, so I was impressed. But will he understand the evening news on TV, definitely no.

About Americans.. you can see why it is so difficult for them simply by listening to Russians speak English. I can safely say that in the US & Canada, the European nationality that has the most difficulty with English - that I've come across - is easily the Russians. Some Russians adults (of course kids are another story) will lose their accent in time, but it quite rare and usually those came over in their 20s. They also have a hell of a time with English grammar. Especially "a" and "the". The reason Russians have such problems compared to other Europeans is that much of English is just that much more foreign to them, and same goes for English speakers in relation to the Russian language. Even simple things often in Russian do not have a 1:1 mapping to English... like many of the prepositions.