There was a great article at, of all places, HuffPo this week. It's by Angela Fluornoy and it's called On Dialect, Dialogue and Good Books. She really nailed one point perfectly. Here's a rather lengthy excerpt (since I doubt you'll follow the link to read it):
In my experience, the dialogue that borders on tiring (which really isn't the right word -- I'd say challenging) is that which focuses on spelling words differently to highlight pronunciation (phonology) instead of taking the time to depict how a dialect is syntactically different.
Example (made up by me): "Dey iz headed to da pictsha show."
