[Content warning: oh gee whiz, the book has just about all of them.]
This book is a survey of sketchy places on the internet… and it gets pretty darned sketchy.
Some of it is mostly harmless. The author orders drugs from a market of pseudonymous folks, exploring how to track reputation in an illegal market. He hangs out behind the scenes at a camgirl show.
And there's the potentially-helpful / but still sketchy areas. He talks to folks at online support groups for people with eating disorders, suicidal people, other folks doing self-harm. The good news is that these people can find and help each other. The bad news is that some of this help is anti-helpful: people with eating disorders reinforcing each others' problems. The worse news is that a few mean people want to prey on the vulnerable people; and thanks to these support groups, the mean people can also find and "help" them.
And there's the worst of the worst. There are child pornographers out there; the book discusses their tactics.
I read this book because it was recommended for me by The Storygraph. It's well-written and parts of it are relevant to my interests. On the other hand, the parts that weren't relevant to my interests were not fun. This book gets dark! I should be more skeptical of these automated book recommendations; this book kinda intense for something I just stumbled into while following a generic recommendation.