This is a whole new level of writing badly, well beyond a mere lack of knowledge of spelling, grammar, and other useful mechanics.
It was a dark and stormy night; the rain fell in torrents--except at occasional intervals, when it was checked by a violent gust of wind which swept up the streets (for it is in London that our scene lies), rattling along the housetops, and fiercely agitating the scanty flame of the lamps that struggled against the darkness.
There is nothing wrong with the spelling, and the grammar, while rather Victorian, is not incorrect. The asides, the superfluous details, the style, and the sheer length and tortuous structure of the sentence work together to produce some notably bad writing. The same description could be written in a much more readable and enjoyable way--but we won't be doing that today.
Another example of purpose-written bad fiction, sadly, was not only published but sold well and is still in print. Naked Came the Stranger was written in 1969 by a team of twenty-four Newsday writers. Each person got one chapter and were instructed to write them independently, provide no character development, no coherence, and a minimum of two sex scenes. The first draft was a disaster--it actually had some small amount of quality, with coherent and articulate sentences. After relentless editing, they pounded the manuscript into a pile of stereotypes, clichés, and turgid, unbelievable sex scenes set in a plot which did not have any kind of continuity from one chapter to the next beyond the premise of a suburban housewife setting out to seduce every man in the neighbourhood. It had nearly hit the bestseller list in its own right when the story of the hoax leaked out... at which point sales went through the roof and Newsday was flooded with requests to interview the authors.
And yet despite the difficulty of deliberately writing truly awful prose, many authors do it so regularly by accident that there are a number of contests set up to, er, reward them. "Philosophy and Literature" used to run the Bad Writing Contest, focusing on incomprehensible academic writing, and "The Literary Review" runs the dreaded Bad Sex in Fiction Prize, focusing on the worst sex scenes in a serious novel (this year, won by Tom Wolfe for his latest novel "I am Charlotte Simmons").
What distinguishes truly awful writing from the rest? The prize winners all have respectable spelling, grammar, and sentence structure--that isn't even in the criteria. The same content (such as Bulwer-Lytton's "dark and stormy night") can be done well, indifferently, or truly horribly. I think that, like good writing, truly awful writing is a matter of style, angle, and presentation.
Style and presentation, both good and bad, are fairly subjective. There are, however, some trends we can see. Word choice is one; good style will use appropriate, precise, and active words while bad style will use inappropriate, possible obscure, possibly incorrect, and probably excessive and vague words. Sentence structure is another part of style, with clear and well-constructed sentences being an obvious part of good style, and excessively long, tortuous, unfocused sentences being part of bad style. Long sentences with multiple clauses can be used in good style, if they are focused, clear, and (especially) the reader does not lose track of it, and short sentences can still have bad style, however.
Angle is also fairly subjective. Originality in writing is generally held to be finding a "fresh angle" on an old subject, so the immediate thought is that bad writing will use an old, tired, banal, and clichéd angle on its subject. Sometimes, bad writing will have a new angle, but it may be an unappealing or inappropriate one.
What do you think makes truly awful writing stand out from the rest?