LJK asked:

"Actually, could you tell me what some of the many things Sagan said were "bogus"?"

Nuclear winter is the most famous example. Also, Sagan wasn't shy about taking one of his existing publications, modifying it very slightly and then republishing it with a different journal. Sagan did some dodgy stuff with exobiology. To Sagan's credit, he was going to coauthor an exobiology paper with Gil Levin but realized that Levin was a flake and bailed out (Sagan had some integrity). I've heard old hands from JPL comment that the only time they saw Sagan was when the news media was around. It has been said that Sagan's greatest scientific acheivement was marrying Lynn Margulis (who later divorced him). Lynn Margulis is unquestionably a first rate scientist. She did pioneering work with mirochondria origins and developed the Gaia hypothesis with James Lovelock.

Gary