PS. Speaking of crossing thresholds, if you forget to remove your shoes and put on the "guest тапочки" within 1.5 nanometers of the door, you are a horribly rude person who was obviously raised by wolves.
Also true
Comes from a problem that most of the people in Russia travel by public transportation and the roads are also quite dirty
Considering that many houses in the US have carpet flooring I would listen to Russians