the competition's pretty stiff...
besides the obvious undeserved successes (the Left Behind series comes to mind) there are famously bad writers who in this day & age have generated their own cult followings e.g. Harry Stephen Keeler, William McGonagall, Amanda Ros, & the redoubtable Lionel Fanthorpe; but due to the following anecdote i nominate Harold Robbins:
"Michael Korda...was working as an editor at Simon & Schuster, and a few years ago he wrote a memoir of those days, entitled Another Life. ...Harold Robbins...started writing one book to get the advance, wrote half of it, and put it aside. When he needed the money, he finished it, but he'd forgotten much of the first part, and so the second part had an inconsistent plot with mostly different characters. Asked what to do about it, he said, 'Leave it.' (Korda is too professional to say which, but I believe it was The Pirate.)" --Arthur Hlavaty in Derogatory Reference (now Nice Distinctions) 3
however, some friends of mine unreservedly recommend Sheba the Seductive Russian Spy:
http://www.amazon.com/Sheba-Seductive-R ... 1561678015
PS it was none other than Catullus who referred to himself as the "worst of all poets"...
_________________
"I have always found that Angels have the vanity
to speak of themselves as the only wise; this they
do with a confident insolence sprouting from systematic
reasoning." --William Blake