Mr. Buckley starts right in, in this return engagement of an always-popular Firing Line guest: "Why did you choose a title so nasty as the title you have given to this book?" Mr. Koch: "He is a mean-spirited person. And let me say this: I like him personally--I mean, in conversation, one to one, he is a charming person, and I don't regret the fact that I was one of four people who made it possible for him to win the first time." But, says the former mayor, Mr. Giuliani has a personality flaw that has undercut much of the good he has done (as when, for example, he fired Police Commissioner Bratton because he "was getting part of the credit" (cf. Firing Line #S1206) and that would unfit him for the Senate (this being before Mr. Giuliani's campaign to oppose Hillary Clinton for Daniel Patrick Moynihan's old seat disintegrated): "The fact is that Giuliani cannot work in the Senate because he can't work with anybody. He must have his way, and in the Senate you can't do that."