I mean, why do we DO this?! It's all so very confusing. Let's think about this historically, mind you. I think the whole reason the user review began was to give businesses a chance to have regular folk speak out about products that they love or don't really love rather than having professional paid writers/reviewers do it, probably with a percentage of them being slipped a dollar or two to lean one way or the other. That's how it started, I think.
Like many decent ideas, this has completely gone astray. These days, you have people with absolutely no idea what they're talking about whatsoever saying "this is the greatest" and then you purchase said product and you're like, um, this is bloody awful. So, what's the point? I know, you're going to say "it's all a matter of opinion". Is it though? I would argue 'no'.
For example, this has been a long standing argument in the film category for decades, where one person says film A is better than film B. Sure, this is where subjectivity comes in...provided that the person(s) doing the talking has actually some knowledge about film ('...knowledge', you say? What's that?!). Have you ever been in a conversation with two 10 year olds arguing over which cartoon is better?! That's what it's like. If you have no knowledge on said topic, you can't possibly defend your position. This is one area where user reviews have really failed for any Joe Schmoe can leave a review and have absolutely zero clue about what they're saying, and you, the reader, don't really have any idea if the source is trustworthy. Ah, but it says 5 stars, right?! It HAS to be good!
Another major failure is that the paid reviewers actually knew how to write and use grammar, etc. Wow, that's really gone out the window, hasn't it? Ugh. Some argue that language skills are overrated and unimportant (all that matters is math, right??) but I would still say that without communication you might have the greatest ideas in the world but no one will ever know about them if you can't share that info.
And then, lastly, user reviews can fall into the category of "business wars", where people have a weird biased competitive liking of a certain business so they'll post over bloated reviews just to pump up sales and state their opinion. Even worse, the business itself will have their friends and family post bloated reviews just so they show up higher in the lists, or purposely post negative reviews about other businesses to try and drag them down. I also can't fail to mention the most bizarre of the user review...the one that is reviewing, say, the material on a CD or album and instead it's talking about how the UPS man delivered the product 2 days late. Stranger even yet, there's also the occurrence where the category could be about a movie and the reviewer is instead talking about a video game. It's all very puzzling.
I think there's only one thing to do, really, and that is to completely nix the user review idea and (gulp) go back to professional reviewers. Having said that, we do need to put regulations into place so that businesses can't pay to inflate their sales but we've really no other choice. The way things are, there's a billion tons of data out there for us to peruse; unfortunately, it's 90% garbage.