what a great thread!
At the moment I can't think of many, but one author does immediately spring to mind - Thomas Hardy. I still have flashbacks to the tedium of his novels.
Mind you he was a balanced man - he had a chip on both shoulders
As to others, a recent one is a Sebastian Faulks book I picked up in a 2nd hand shop and was beyond dull - The Girl at the Lion D'Or. And I'm still cross with myself for bothering to finish it, I should have taken it back after the 1st few pages!
I'll have to go and think about others