Online reviews, of every ilk, should be taken with a jaundiced eye.
First consideration is whether the review base actually applies to the product in question. Amazon has long allowed recycled item listings, and doesn't reset and clear out the non-applicable reviews, even if they are for a completely different product, which poisons the numerical data. This is most evident when a third-party seller pivots from selling something like electronics, to women's clothing. Looking at the items in the seller's storefront is also a good way to filter out those who are simply dabblers, who might sell a random variety of stuff, versus those who have more a plan, commit to selling specific types of products, and might not be as likely to fly-by-night and bail after selling through their stock.
Second consideration is whether the bulk of the reviews apply to the specific model, or variant of the item in question. Same as the first, to a lesser degree. The sub-heading to each review specifies the model, or variant the buyer is reviewing. But that only works well when item listing is properly-written, with each option carrying accurate descriptions. But still, the overall ratings are compiled from the all reviews, and it is up to the shopper to differentiate between what is applicable, and what is not. A bunch of five-star reviews for that 1000W microwave oven is going to drown out the three-star reviews for the underpowered 700W model, and skew the numbers. It's up to the shopper to comb through each review and pick out those that really are applicable, and not rely solely on the stars.
A few years ago, Amazon reviews were riddled with the "I got this for free, but this is still an impartial review" type of reviews. Yeah, sure. Sellers were gaming the review system by providing free products to anyone who had a pulse, which resulted in a lot of low quality reviews from unqualified people flooding the system with less critical, mostly positive reviews. In a rare bit of clarity, Amazon then decided to ban the biggest practitioners of these practices, and purge those products from its store. But, that also served to throw the baby out with the bathwater, because some of those products actually were legit, and didn't stop the practice. That move only drove it underground, and it still occurs today, even if to a lesser degree. Amazon even officially makes it part of their system, through the Vine program, but at least those are clearly identified.
Amazon's review system has a lot of structural deficiencies it has long failed to address, or correct, so it cannot be blindly trusted. It's a participation sport, and the best place to start is not by trusting the good reviews, but looking at the bad ones and taking the valid ones into consideration. Their customer service is still good, and liberal with taking returns. But relying on that avenue puts one at risk of being banned as a customer as well, even if for legitimate reasons. Shipping non-vetted, returned items in damaged condition as "new" is already another issue the company has.
At the most basic level, one also has to have faith that the people writing the reviews know *** they're talking about. That is often not the case, and I've seen glaring instances where reviews were based on plain factual errors and poor knowledge, especially when it comes to more technical respects, like understanding a safety mark and what it means. There used to be a provision where responses were allowed, but it was removed, so the only options now are to mark a defective review as helpful, or "report" it.
