I don't know, I've been here almost 8 years, maybe it's me but I have really experience nothing but friendly locals. Of course, I really try and dig in with the language and surround myself with local friends, etc.
Of course, there are a lot of rude and ornery people here, but no more than any other countries that I have lived.
In fact, if you want to talk about rude, obnoxious, disgusting people, try Singapore or China (where I lived the last 2 years). They make the Argentine people look like angels. I was SO eager to leave Asia I had a calendar with a count-down of my returning flight.
Enjoy, smile, help when you see someone in need....it will come back to you.