That's just sad... that's why so many people just stoped being nice to each other...
But if you stop being nice for fear of what others will do, than you let those rude people have it their way...
I remember this one lady at work... I would greet her with a smile and a "good morning" and she would just give me a blank (almost annoyed) look and she would look the other way...
It took me a few months... but eventually she started to greet me back... hehehehe
"MISSÃO DADA É MISSÃO CUMPRIDA" (Mission given is mission accomplished)