Language is complicated, flexible, and always in transformation. Being a speaker of English, I have tens of thousands of words at my disposal to use as tools to communicate. Besides the words themselves, the definitions behind them can be varied and nuanced. To accurately express a thought or feeling takes some time, skill and patience to come up with just the right word choices. Throwing punctuation into the equation complicates things even further, but necessarily. Spoken words are equally complex, in that they include volume, inflection, speed of speech, facial expression and attitude--all of which are the verbal forms of punctuation.
Bad speech or writing communicates just like good speech or writing. You know something about their author: Do they pay attention to detail? Can they spell? Do they care to communicate clearly, or do they presume their readers or listeners can read their minds? Do they communicate directly, or do they rely on sarcasm and innuendo, or hide behind jargon and popular opinion? Do they care if they offend? Do they consider the receiver of their words and take consideration of how they want their words received?
My father, a woodworker, always said "Measure twice, cut once." Users of language would do well to use a similar maxim: "Think, then think again, before you speak." The choice of words, how they are spoken, and consideration for who is receiving those words can make all the difference in how effectively and successfully those words communicate the intended meaning.