What is the ugly side of Korean culture?

First, alcohol culture(dringking culture.).
The ugly side of Korean culture is alcohol culture.
Most of Korean people intimidate other people through alcohol, even though they are just trying to be friends. They are very very excessive.
For example, primary is an restaurant, secondary is only alcohol and
tertiatry is singing rooms. The Korea culture is very cxpensive and tiring. Also alcohol is very bad for your health.

Second, education culture.
The zeal for children's education in Korea is high. Because of this, children go to private education institutions since early years.
Children can't have deep sleep or rest time. Deep sleep or rest time of
Korea children is just 3hours. The 3hours is used for homework.
They will ge very tired. This situation causes many problems these days.
For example, kill moeself and mental illness..etc...

These are the ugly sides of Korean cultures!!!

If I visit a person's home in Korea what should I do?

First, table manners.
If foreigners visit a home in Korea. When eat food, you should say the food is delicious, even if it is not
because foreigner is little hard-hitting. For example, the spicy food is not delicious for foreigner. So they can say "Oh, it is not delicious." And then mother feels disappointed. Finally, if foreigner feel unaccustomed taste. They should not say "It is not delicious."

Secomd, table manners.
When eat food, you should not before eat than adult. It is traditional table manner in Korea.
For example, never begin eating until everyone is seated and the adults starteating.
And say " I freatefully receive" before meal and " Thank you for the meal" after meal.