Just as it is easy to misinterpret the reason for an icebreaker activity, it’s easy to mistake certain social customs of Americans that might suggest strong personal connections where none are intended. For example, Americans are more likely than those from many cultures to smile at strangers and to engage in personal discussions with people they hardly know. Others may interpret this “friendliness” as an offer of friendship. Later, when the Americans don’t follow through on their unintended offer, those other cultures often accuse them of being “fake” or “hypocritical.”
Also:
...[a] Russian saying “If we pass a stranger on the street who is smiling, we know with certainty that that person is crazy . . . or else American.”
From The Culture Map