I would want to know the author's educational background, what other books they had written, what awards they garnered. I'd Google them, read the wiki, see if their works had been covered in important book review publications. I would do that to at least sort of determine their legitimacy and if they looked ok and the topic interested me I would then buy the book.

I do not discount Amazon reviews in making that assessment as they can often be quite informative, especially regarding non-fiction.

The thing is, so much of what I learned in college and grad school fifty years ago has now been deemed bullshit. Plate tectonics was heresy. Genes never changed. Animals were Pavlovian mechanisms. And so on and on and on. You can only do the best with info available at the time and know that nothing is written in stone. Education never stops.