seriously, treating people as non-existent is the most hurtful thing.
be it on purpose or not.
your bad day becomes my bad day.

but well, one should more or less be used to this if they grow up in this kind of environment.
thus changing of mindset, changing of oneself so that one can integrate to the norms of what people are doing.

when you're talking to a person, look at him/her.
isn't that basic courtesy?

how crappy can a day get.