It often amazes me that people (who sometimes call themselves ‘authors’) don’t think anyone would catch them when they plagiarise stuff. (Yes, this is a direct response to this issue here.) It’s something I’ve come across pretty often as an editor, though nothing quite as egregious as in the book in the link.
Usually it’s a paragraph or two or three, sneakily inserted in the middle of a chapter. Sometimes writers get away with it, sure. Most of the time the editors notice. There’s always a change in tone, or the style of writing, or even in vocabulary and word choice when you copy something directly instead of rewriting it in your own words. There were times I got suspicious simply because the word order and emphasis were a little off. Other times it was because the language suddenly became perfectly correct when earlier there were always some grammar mistakes here and there.
I’m also partly amused and wholly annoyed that the first response from a lot of readers is ‘where’s the editor?’, like the author himself isn’t the first person to blame for knowingly copying content from the internet. It’s not like it’s something you can do accidentally, guys. It’s something you do with intent, on purpose, for no other reason than to make people believe you wrote something you didn’t. Frankly, if a submission that bad came across my desk, I would just firmly say no and refuse to edit it. I’ve done it before, even when I was working with a publishing house. I simply told my boss I wasn’t going to sign this off if it wasn’t completely rewritten (and that had been one short chapter, not a whole book). The manuscript never went to press.
Just because you’re self-published and there’s no editor to catch you doesn’t mean that you can do whatever you want. There are copyright laws out there, and oh, I don’t know, common sense and decency.
Don’t plagiarise. Use your own words. Cite your sources. Be a responsible writer.