Americans love a friendly smile when it seems appropriate. The only problem is that Japanese smile for various reasons, including when they are embarrassed, apologetic and mentioning un–fortunate events. Someone who knows Japanese well can distinguish between these “types” of smiles and recognize the emotions they express, because they have long experience with other people who do this. But many Americans do not, so they are likely to misinterpret the reasons for the smile.
If a Japanese smiles as he apologizes, it may seem to the American that he is not only un–apologetic but actually making fun of the American. If a Japanese smiles when he announces some sad happening in her family, it may seem to the American that she is insensitive and even cruel. The whole problem is one of differences in body language.