I don't know why this bothered me....As I was walking into a grocery store yesterday, a guy from the Salvation Army collecting donations said something like "Good Evening!". There were about six people entering the store at the same time as me...only two of us replied "Good Evening!" back. The rest pretended like they didn't even see him. Now I can see why some people don't want to START a conversation or greeting with a stranger. It can be scary. But if someone speaks first I think it is totally rude not to reply. Gosh why must some people have a stick so far up their ass that they can't acknowledge someone for a few seconds?