[Cadabrum]

That is not true. In western countries one must smile to be polite, even if the smile doesn't represent his/her current mood. There is no objective reason to render happines in common situation for Russian people.

One may smile when he meets a friend or sees some cute kitten, but in general people are walking in some meditation alike state, thinking about the current affairs and not particularly paying attention to the people they passing by.

And when russian person meets the grinning stranger with cold eyes (not his real mood). It looks kind of creepy. Ordinary people usually do not pay much attention for this kind of encounters. Police (are you drunk?) and street scammers(are you a tourist?) - do.

[varjag]

It has little to do with meditation, it's an ever present tension imposed by simmering-hostile environment that most Russians live in. In the same vein it's a common Russian misconception that Westerners always fake their smiles. They are often genuinely more friendly and chill.

And yes, if you smile too much you are taken for лох, even if you are native. Get to an urban market some day and smile to sellers, посчитай на сколько обуют.