"Clouded his memory"
Not even Time magazine's Romesh Ratnesar seems very impressed with Richard Clarke's veracity:
The accounts of high-level conversations and meetings given by Clarke in various television appearances, beginning with the 60 Minutes interview, differ in significant respects from the recollections of a former top counterterrorism official who participated in the same conversations and meetings: Richard Clarke. In several cases, the version of events provided by Clarke this week include details and embellishments that do not appear in his new book, Against All Enemies. While the discrepancies do not, on their own, discredit Clarke's larger arguments, they do raise questions about whether Clarke's eagerness to publicize his story and rip the Bush Administration have clouded his memory of the facts.
Read -- once again -- the whole thing.