In my defense what I have to say is that I have no qualms with rude, vulgar or slang words.
Perhaps I didn´t express myself well, so I might have been misunderstood. So, my posting had two main points, that of New Yorkers using their colourful language to the point of being seen as rude, that is a fact.
That happens in Brazil as well, when people of Rio de Janeiro city may use our colourful language as well, the way we see people speaking to the other saying "mané" or "vagabundo" for instance, or other ways (to a friend in general conversation).
And they don´t mean any harm or derogatory statement, it´s just a way of speaking. Anyway as a guy that have been into language for awhile, I have to let a learner from abroad to know that a region has its mores and ways, but what works in a region may not work in another.
Conversely, the learner of English must be aware of such differences as well, not only about language but culture and way of life, etc.
As I pointed out variety is the spice of life. And fair enough, pretty much anyone just having hit his thumb will use an expletive, or will learn one on the spot!