Interesting questions, Puma.
I'm responding to this this as an English type fellow who has seen a few Western films and TV shows; read a handful of Western novels; studied (though not too hard as my future mistakes will no doubt reveal) American history; read a few of the first piece's of American literature and lived in the States (north east US) for a year. I say this to give an overview of my dilettante engagement with the subject, that is to say, I know a bit, but really I am an amateur with a bit of an opinion who wants to learn more.
I think one answer to the initial question posed in this thread depends on the type of piece being written, the characters involved and a certain amount of poetic licence. For instance, Puma's piece in SYW was only the worst offender with stereotypical language because it was the most comedic; and, because of that, the use of slang can easily be considered the best due to the tone of the piece.
The characters involved in a story are important, too. Perhaps they are Okies and then should sound like them. Or, perhaps they are North Easterners and should, therefore, sound like North Easterners. The interesting point this raises is how
did they sound? How far does an author go in getting it spot-on-historically correct?
Dave Hardy and CDaniels's posts are most helpful in answer to this.
It's clear from DH's post that language was wide and varied and people were aware of the acceptable types of language to be used in different circumstances. I think when we write we can take a lesson from this. Just as a contemporary person will use different language around his friends, workmates, family; so will someone from the past. The question is, how far did they go? If you want authenticity (or as close as you can get to it) a good way to find out what they'd actually say is to look at the sources DH lists.
CD gives a good example, too. I'm loosely aware the language used in the remake of
True Grit was pretty faithful to the source novel and I think (iirc) the source novel is meant to be a pretty well done version of 'how people talked at the time' and it's all the better for it. There is something wonderfully amusing, scary and 'authentic' about the matter of fact way the characters talk in that adaptation. This odd style of no frills, non-contracted speech, would also be a good way to go to avoid the stereotypical and mine the 'real'.
Finally -- if i may jump the gun and respond to your question about swearing in the west and westerns before CDaniel -- I would say that when a cowboy fell from his horse in 1870 he would probably say the same as a cowboy who fell from his horse in 1990.
With that said, what he/she says is also dependent on a few factors ...
* What type of person the cowboy is. He may have religion. He may be a drunkard. He maybe an American Okie or a European immigrant. These factors (and a not exhaustive list of others) will affect the curse -- if indeed he does curse rather than laugh or cry -- he emits when bucked.
* What type of piece is being written. Classical Western in the film or novel form. Revisionist Western. Modern western. Sci-fi western. Comedy Western and so on and so forth.
* The perspective and intent of the writer and his/her audience. I think this and the previous point are suggesting that whilst 'authenticity' is important and difficult to achieve, it's totally fine to write something within the genre rules that you feel happiest within.
It would be most interesting to explore this in a future prompt. For example, write a Western piece in the classical style or write a revisionist western etc.
All in all this is a fascinating thing to think about, especially for me who is learning the ropes of genre -- not only from film, novels and books, but also from what people write in SYW and real Western type people, too.
Oh, I should add as a post script that I am liquored up so I hope this long post made sense and wasn't too hard to get through.
