It's the content. Hatred, bigotry, idiocy, the occasional outright lie...
Those so inclined can go to
http://www.chick.com
Jack Chick writes Christian comic books. "So what?", you say. Dear Reader, you are obviously not familiar with what lurks in the lowest reaches of the American religion. I first encountered Chick's work as an undergraduate at Berkeley --- someone had been passing them out on the main campus square, and one of them found its way to the physics society. This classic was entitled Big Daddy? and the cover was graced by a grinning chimpanzee eating a banana. It told the story of the conflict between a born-again Christian high school student (who looked like a Hitler Youth recruiting poster) and his science teacher (who looked, not to put too fine a point on it, remarkably "Jewish"). The science teacher attempted to indoctrinate his class with the vile doctrines of secular humanism, an old earth and evolution: but the stalwart young man stood firm, secure in his God and his faith, and finally confuted him with the nucleus of the atom. Here, he said, were all these protons, of like charge, bound together: but don't like charges repel? What holds them together? The teacher is bereft, sweating, without answer. The youth triumphantly says, "Our Lord, Jesus Christ," and cites an epistle to the Colossians. The class is converted; I forget what happens to the teacher [he got the sack -JF]. Most of us were taking nuclear physics at the time...
[Some explanation may be necessary here. The forces holding atoms together are not familiar from everyday experience, but they are very well understood by nuclear physicists, thanks to decades of scientific experiments. Saying that "Jesus holds atoms together" is as hilariously ignorant as claiming that planets travel in ellipses because angels are pushing them around. -JF]
Mr. Chick has been turning out this stuff since the '60s, and beneath the intense ignorance, anti-Catholicism, creationism, blood and gore, homophobia, sadistic fantasies about Hell, paranoid fantasies about Satanism, drugs and the apocalypse, and vicious resentment of others' prosperity (the only thing missing is explicit anti- semitism) --- or perhaps, because of all that --- there's a great deal of unintentional humor. It's an acquired taste, I admit.