I was in Riga and could not tell a difference between the Estonians / Latvians with Russians.  Colour coding does not work and I personally offended a couple of brunettes when I mistook them for Russian.  :D  ;D

The visa requirements kept me away but I assume St. Petersburg is similiar to Riga.  With one exception, while most of Eastern Europe has been spared, Russia in particular has a slight issue with internal migration (Rossiyane Asiatics moving to Moscow and sometimes, although rarely, to St. Petersburg).