This is one more stereotype, though more thorough. Many Russians like this stereotype and there is "a grain of truth in it" as always. But in fact these tendencies are not polar: there is a long cultural staircase of sincerity vs politeness. I remember young Tajiks in Dushanbe, they were more sincere and less polite than Russian-spoken people. And maybe, let us say, Japanese are more polite and less sincere than "Western" standard implies, idunno.