Russians do not smile at strangers
Russia is a collective culture, consisting of ’in-groups’. Russians do smile at people they know. Shop assistants smile at the clients they already know, not necessarily at others.
If you smile at a stranger in Russia, he/she can smile back, but it can already mean an invitation to come and talk. Russians take smiling as a sign that the person cares about them. To smile at a stranger can raise the question:” Do we know each other?”
You see two behaviours in one person in Russia: formal – unsmiling is for ’them’ (strangers); friendly – smiling for ’us’ (friends, people he/she knows). Some Russians skip to friendlier behaviour after a shorter time. You can consider yourself accepted when people you have met begin smiling at you.
Real feeling – not fake
Smiling in Russia usually shows the real good mood and good relationship between people, as it is not used as a form of politeness. When a Russian smiles at you, he/she really cares about you or is genuinely in a good mood.
How to smile
Russians prefer not to show their teeth too much when smiling. Showing your upper and lower teeth when smiling, looks a bit vulgar, a horse grin to Russians.
Smiling without a reason
Others must understand the reason of smiling in Russia. If they don’t, it is considered strange. They start wondering what is behind the smile. Perhaps they interpret that the person who ”keeps smiling” is a bit simple or stupid. All Russians know the saying: “The laugh without reason – is the sign of stupidity” (“Smeh bez prichiny – priznak durachiny”)
Pretty sure if was in Kumarajiva’s Commentary on the Great Perfection of Wisdom that I read a passage about how a man should not show his teeth when smiling; a smile should be demure or none at all. Smiles can be understood very differently in different places. ABN
American Buddhist Net 