I have lived in many cities and towns and most sections of the US...in Philly, they will curse you out while they're picking you up.....calling you a fucking idiot as they hand you coffee....
New York...I found to be very friendly; but, then again...I grew up in Philly....
The South? Well, most people know my experience there was simply awful...but, does that speak for the entire south? I don't think so....it was just where we were and who we were with that coloured our experience so poorly.
Jamaica. Now there's a place. Stayed in Negril the year people were rioting in Montego Bay.....we were told to stay in the compound because the natives were selling pot to the rich Americans and then turning them into the police. Saw it happen...it was actually funny....staying in a place like Couples or Sandals or whatever it was...watching a guy buy pot and then five minutes later the Jamaican police swooped down and took the poor schmuck to jail....they didn't want to keep him....just wanted to confiscate the pot and fine him....nice cottage industry.
I live in Seattle now....and I kind of miss my East coast blunt....direct....in ya face kind of people...the overly polite, stoicism I find here is kind of alienating..and I am constantly walking around saying, 'don't mind me..it's a cultural thing'.....folks here will ask you how you are as they step over your bleeding body....
Still, no matter where I have lived..no matter what idiosyncratic behaviour exists amongst the people.....smile and the world will generally respond favourably....manners do get results no matter where we are....