Honestly, almost all horrible fanfic is deliberately bad. They write it for whatever entertainment reasons they wrote it for, so it's only fitting to enjoy such things. I will steadfastly and aggressively defend this position to the death.
As for the genuinely awful authors, they usually do improve in some manner or another, or at least stop writing. A person with a large body of bad writing is a fake, though Amanda McKittrick Ros is certainly an exception to this rule.
