I'm the middle of reading a long locked thread on a message board about how to write black characters and to make their dialect and language sound believable. Well, not surprisingly, the thread dived into the racism debate, but it provides good reading. How important is it to for writers to write their characters with dialects? I have never done it. I would find it too hard and would worry that people could understand what they were saying.
If a character is written with a dialect or speaks with slang is that a racist sterotype? I think people throw around the word racist far too easily these days. The world has become too politically correct. I don't think it's racist to write a character, especially a black one, with a dialect or to include slang in their speech. It can be a cliche or a sterotype though and that is something all writer's must avoid.
For example I am Australian. I do not say "G-day, Mate!" or "Crikey!" or call my friends "Mate!" but I know other Australians who do. It does irritate me when I see Australian characters on American television shows who have the cockey accent and say "Mate" and "G-day" every two seconds. It's such a big fat cliche!!
Dialects and slang should be used like other forms of description. Less is more. If you put too much in you risk coming across as racist and being cliched and encouraging sterotypes. If you do it just right though you can make a believable character. In the book I am reading at the moment the main character is from the South in America. The author slips in her accent every so often in bits of dialogue and even has her slip into french a few times. It's really good and believable.