You ever notice how people only give salams to other people they know? This is not from the best Islamic character. Instead, we should give salams to those we know and those we don't know. A man asked the Prophet (S.A.W), "What Islamic traits are the best?" The Prophet (S.A.W) said, "Feed the people, and greet those whom you know and those whom you do not know." [narrated by Abdullah ibn Amr in Bukhari]