“Talk, whether ugly or beautiful, is an index of character; it can also be a breath of cool, refreshing air in a room some people would prefer to keep shut up. In the end, the important question has nothing to do with whether the talk in your story is sacred or profane; the only question is how it rings on the page and in the ear. If you expect it to ring true, then you must talk yourself. Even more important, you must shut up and listen to others talk.”

Stephen King on the relationship between isolating yourself and bad dialogue (from On Writing)