I agree with you that staring or smiling at strangers here in America may be considered rude or malicious by most foreigners. When I got here in America, I often startled and felt uncomfortable that people here or strangers would greet me and smile at me in public. I totally find that very strange because I believe in most Asian cultures, smiling at strangers in public may show affection or disguise true feelings. However, now that I have already adjusted to the American lifestyle, greeting or smiling at strangers is not an issue to me at all; yet, I am very cautious with whom I smile at.
-Maria