RUSSIA: Not bringing a gift
Speak to any Russian and they will tell you that you cannot visit a household in Russia without bringing a gift as a sign of respect. Come empty-handed and your gesture, or lack thereof, will be considered rude and disrespectful.
You don’t even have to bring something expensive, some chocolate and alcohol will help you pass the test successfully. To impress your hosts, you can also bring something specific to the region you are coming from. That will help you score even more points!