I have not read it, obviously, but the title and cover of Jonah Goldberg's book are mistakes.
Feel free to make the argument that fascism and Nazism are movements of the left, but calling liberals fascists and hinting they are Nazis is just plain wrong. Franklin Roosevelt created modern liberalism as a democratic alternative to fascism, communism, and Nazism, for crying out loud. The way the blurbs for the book read, it sounds like he is making very un-Goldberg-like arguments, like saying Hitler banned smoking and liberals want to ban smoking, so liberals are like Hitler. This style of argument is much like saying the SS used rifles and the U.S. Army uses rifles, so the U.S. Army is just like the SS. The point is that the SS using rifles is not what made them the SS. Hitler and the Nazis banning smoking is not what made them Hitler and the Nazis.
Again, I haven't read the book. I know Goldberg is a smart guy. I know he usually is the first one to point out how silly these types of arguments are. And I know he did a lot of research on the topic. I will probably read the book to see what he came up with. But the title, cover, and blurbs on the Amazon page are a disastrous start.
(Hat tip to DCAT--so don't call us hypocrites.)