The first 1/3 of the book reads like an expansive and poly-sourced mega blog entry. Not in a pejorative sense! I live for well-informed blog entries. :-P Just lots of editorializing involved.
Dr. Sagan provides many compelling points to debunk the UFO theories (e.g. NSA secrecy during the Cold War) or alien abductions (e.g. sleep paralysis, suggestive and mildly schizophrenic people). But I was a little taken aback by his accusatory tone. Perhaps it stemmed from the frustration of dealing with this ignoramus-masses issue for many years. And his failing health at that time... the book was published in 1995.
Last page of the alien chapter:
Despite this apparent variety of extraterrestrials, the UFO abduction syndrome portrays, it seems to me, a banal Universe. The form of the supposed aliens is marked by a failure of the imagination and a preoccupation with human concerns.
But Dr. Sagan should have given these people a break because the general public really doesn't have the combined technical and imaginative prowess of astronomers. :-P
Not a single being presented in all these accounts is as astonishing as a cockatoo would be if you had never before beheld a bird. Any protozoology or bacteriology or mycology textbook is filled with wonders that far outshine the most exotic descriptions of the alien abductionists.
The believers take the common elements in their stories as tokens of verisimilitude, rather than as evidence that they have contrived their stories out of a shared culture and biology.