Maybe re-phrase the question - I ONLY trust negative reviews now. The key is to see how many people have negative reviews and then scan them.
Let's say I am interested in a BBQ Grill.
10 reviews about an open box/returned box? I'll probably go to a local CampingWorld and pick it up instead of Amazon and pay the extra $50.
4 people say the grill grate is bent but there are 1200 other reviews that don't seem to have a problem? Low chance I'm going to get the bent grill grate.
There are a ton of Facebook groups out there whose sole purpose is to shove $$$ into paid reviews on Amazon (or Yelp, or other review sites). Could be a bunch of college kids looking to make a quick buck, or maybe some broken-English dude from some 3rd world country who actually made it their full time job. I don't know, but that's not the point.
The point is: you can literally buy Amazon reviews (or Yelp reviews, or ... any kind of review really) from Facebook groups, if you know where to look.
What I look for is bad reviews that indicate to me the problem is PEBKAC - nobody is buying bad reviews, but if the only real complaint is that when someone dropped it on their toes it hurt, then it's probably OK.
But more and more I lean toward "if I have to get it from Amazon it needs to be something I'd be happy with being crap".
There's also "rival company" reviews. I've heard from some business friends in the Hotel business that rival Hotels are probably leaving bad reviews on Yelp. And there's pretty much nothing you can do about it.
You look at a review, you back-check the date and try to line it up with customer records. You look for complaints, you ask staff if they remember the customer. Etc. etc. Ultimately, its a phantom, clearly a made-up review designed to hurt your company for some reason.
That's more of a thing on Yelp where if you bad-mouth a neighbor with a fake-review, your own business across the street benefits. Less of a thing on Amazon (where a fake negative review won't necessarily lead to customers buying your thing).
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Back 20 or 30 years ago, a fake negative review on a newspaper or an advertisement would lead to suing the perpetrator for slander or libel. Today, there's no recourse at all. And more-and-more people are learning about the marvels of the modern internet age where you can pretty much slander your opponents and benefit from customers as a result.
And even more devious, companies paying people to leave obviously fake positive reviews for competitors so they get afoul of what little review verification Amazon does, and banned:
This. I look for genuine problems. Works with hotels too - are the negative reviews unreasonable ("Dude, I think you're the problem, not the hotel...") or things that I can see someone like me being upset about occurring ("They say construction is done on the new wing, it's not done and they start at 8 AM...")
That won't last long, negative reviews will get flooded by glowing reviews with trivial complaints. "This thing is perfect except I don't like green so 1/5"
Let's say I am interested in a BBQ Grill.
10 reviews about an open box/returned box? I'll probably go to a local CampingWorld and pick it up instead of Amazon and pay the extra $50.
4 people say the grill grate is bent but there are 1200 other reviews that don't seem to have a problem? Low chance I'm going to get the bent grill grate.
Things like that.