smiling for no reason is insincere and indicates foolishness. There is even a saying in Korea that states, “He who smiles a lot is not a real man.”
According to a Texas Tech guide on studying abroad: ‘Germans, and Europeans in general, might seem rude to most Americans. They smile less frequently than Americans, not because they are unfriendly, but because “unnecessary” smiling is considered superficial and insincere.’
As the Korean saying goes, ‘He who smiles a lot is not a real man.’