If it's a book that's got lots of reviews, it means it's shilled by big publishing companies and is most likely popsci garbage nonsense or recent event controversy bullshit that will most likely become outdated in less than 2 weeks.
If it's a niche title promoted by a few communities, it could either be somewhat good, or it could just have a handful of dedicated shills (or even just sockpuppet accounts managed by the author themselves).
If it's very obscure, it could either be good or absolutely awful, only promoted either for the laughs or promoted by an ultra-narcissistic author who's unwilling to condense their thoughts into a single blog post or a video succinctly explaining all of their main points.
If it's not awful but it is obscure, it could simply be of little interest to the general public.
If it's a book proposing a new theory, it should either be one that must be easy to understand even for people unacquainted to the subject with little patience for fine details, or otherwise it will risk being misunderstood and getting mixed up with other theories it might be loosely connected with (or even with ones it might be trying to stand against).
And if it's shilled by anonymous people on 4chan, it's almost certainly either full of obscure jargon and void of any practical applications or something extremely basic and generic that covers exactly the same topics and themes other books (or instructional material on the same subject-matter do), except dressed up in some edgy flair to attract people who wanna feel special for doing something that's not quite the same thing everyone else does
