Any review can be faked, but you can spot most fakes if details don't make sense. If no details given, then the review is worthless to you anyway.
When someone says the product is "built cheaply," or "built sturdily," I look for the reasons they have for their conclusions. Compared to what? How is it being used?
I look for discussions of product in the reviews, not just a simple conclusion. Sure, we know that likes/dislikes are very subjective, but the most valuable reviews give reasons.
Simple one sentence reviews or just the number of stars, only tell us the reviewer's preference. Not much help to you or me, and may just exist to drive up rating averages. But I have found valuable products even in poorly rated reviews.
The most valuable reviews give reasons; during the review content you can get an idea if the user is similar to you or not, but the discussion helps you understand the product's performance and function for your purposes.
One outstanding example was a review of electric weed wackers. It was obvious that 25% of the reviewers complaining of premature motor burn out could have caused the problem themselves because they were using undersized extension cords, especially when 50% of the reviewers were showing good motor durability for weekly usage that I would likely be giving the product.
It helps to understand reviews and reviewers if you take time to learn how a product should perform and how it should be used. Read CNet performance testing reports, Consumer Reports, or other professional sources to understand what you want/need before reading reviews to help select the reviews which might make the most sense for what you want/need.