I always thought Brock an unpleasant piece of work when he was a conservative character assassin, and now he is a liberal one, I haven't revised my opinion.
If, by that, you mean the book The Real Anita Hill, then you're WAY off the mark. He may claim that it was a "hit piece" now and deny it, but virtually all of the major facts in that book have checked out. Anita Hill perjured herself in a conspiracy to bring down Clarence Thomas that involved the highest level of the Demonrat party, including sitting members of the Judiciary Committee and, especially, their staff.
A chimpanzee could have written that book. The proof is that David Brock did write it.
Brock is a totaly unpleasent piece of work, but he was never a "conservative character assassin." To suggest so assumes that folks like Anita Hill and Uncle Joe Biden ever had any character to begin with.