What's an acceptable amount of non-standard English that can be used to depict the language of a certain area of the South (Louisiana) without turning off readers? My current work in progress has dialogue from a rural community which I know is authentic, but a couple of editors have warned me that its use will turn off some readers. Likewise, I recall several books that I read in a book club that were not well received by some of the other members for the same reason.
You want something that sounds authentic, not is authentic. You are trying to create and impression, not a record or documentary.
You need something readers can understand. 'Huckleberry Finn' uses a number of slang terms but it is easy enough to work out what they mean. They create the character and the place without getting in the way of meaning.
Overdoing regional words and constructions leads readers to give up. It is similar to using foreign language words and phrases in a story -- people start skipping them and then the pages they are on and finally the chapters they're in.