The trick is to read the negative reviews, including up to 3 stars. If there are none, that's a problem. If there are a lot and they make sense, that's a different kind of problem. I ignore ones that are strictly "This is garbage you should have bought X instead" as obvious fakes, just as one should ignore reviews on Yelp claiming the customer at an inn or restaurant saw a roach.
I should have taken my own advice myself recently with some outdoor lights. Once I realized they didn't work properly, I went back to the Amazon product page and read many very recent reviews. That's important, since Amazon will leave old reviews even after a product has been changed. The negative reviews explained exactly why the product was hopelessly inferior and detailed efforts by the other customers to repair them to no avail. Usually I'm more careful; I think I got seduced by the colorful image.
