I trust some reviews of some products by some people. I differentiate. For example, for car reviews I read Edmunds reviews but don't trust all of their opinions. They don't try to do anything with car reliability which really sucks, but they can't. You don't know what's what until you've owned the car for 10 years, and they are reviewing new cars. I trust my mechanic friend much more here since he can actually look under the hood and tell me if the type of car has a transmission that's prone to go bad, or an engine that's going to burn oil. It's possible that he's pulling his opinions out of his own biases, but what he says usually makes internal sense so I feel better if he tells me something is good or bad.
I don't trust good restaurant reviews, and only trust bad ones if they cite specific issues, like using wrong ingredients, etc. I trust my friends and family when they say a place is good or bad much more because I know their tastes and I can ask followup questions.
For electronics, I pretty much don't trust anyone with anything unless something is backed by the manufacturer. I only trust Apple products because of Apple Care. Everyone has had a bad experience with a laptop, a phone, a tablet, a mouse, a USB cable, etc. It's not worth listening to most times since it's usually a horror story from 10 years ago about a company that who's had their entire manufacturing line re-tooled since.
On Amazon for a generic product, the biggest indication to me is if there are lots of reviews. That means lots of people own the product. If most of the reviews are one star, it's a crappy product. If not, it could be good or bad and I personally find very little correlation between the way I perceive a product and its Amazon reviews.