Comment by lostwords

It's quite accurate in terms of approach, but there are a lot of situations where smiling is more or less appropriate and wouldn't be considered as a rude move. For example, it's completely okay (almost) for service people to be smiling and approachable although it's not obligatory in any way (especially at small stores). At the same time if you are just smiling at strangers without saying any word, it could be perceived as a rudeness. If you smile and give a light nod, most people will think that you somehow know them. So, it's not that Russians are all grumpy and angry all the time, but they (we) need to have an explanation for your smile, you just can't smile without a reason, if that makes sense.