You don't have an obligation to somehow save other people from wasting money, and honestly, that's not what you're doing when you post a negative review of someone's work. In truth, what you're doing--and I'm speaking both as a creator and a reviewer, here--is sabotaging somebody's career. The more negative the review, the more damage you're doing.
Is a Negative Review Really Deserved?There are certainly negative reviews that are deserved. Let's say you buy a product that you're using exactly as the directions state, exactly as it's intended. Something in the product itself goes wrong and you suffer an injury because the product itself is flawed. The battery explodes while you're holding it, for example. In this case, you're warning other people of an actual danger in using the product.
In other cases, however, it simply comes down to a subjective issue. If you read a novel, and it's just not to your tastes, it's not an objectively bad novel. You just didn't enjoy reading it. What is it helping by ranting about all the things you hated about the book on a public forum? Did the writer actually come to your house and threaten your family? If not, then what reason do you have to actually torpedo their career?
It's Broken!We've seen this with Star Wars lately, and with other elements of fandom. I've had it happen once or twice with things I've authored, and I have a lot of colleagues who have seen it. Someone buys a new gaming book, and it doesn't work for their campaign or style of play, so they post a review decrying it as, "completely broken," or "unusable." In truth, it's just not their bag. But that review will see other people go, "Oh, well, if it's broken, I won't bother with it." Many of these people might actually have really enjoyed it. So what you've done is not only robbed others of a potentially solid work for their game, you've torpedoed the efforts of a hard-working designer.
I've had people attack books I've written as broken or unusable based on a read of a single chapter dead in the middle of the book, when, had they bothered to read the entire thing, they'd notice that everythng they claimed wasn't there, was actually right up front in chapter 1. Yet, my sales suffered greatly because of that review.
I Have a Responsibility!Look, everyone feels like they have some sort of responsibility to uphold the quality of art, but sadly, it's not that simple. Really, in the end, negative reviews are almost always nothing short of self-serving, self-aggrandizing, and harmful. They almost never help anyone. Yet, there are inevitably those out there who like to hold themselves up as the arbiters of quality, and who (I'm sorry, but very arrogantly) believe they have a right and responsiblity to "force creators to produce better material" with negative reviews.
I'm probably not changing anyone's mind with this, and certainly someone's going to show up to defend their right and responsibility to post hateful things, and to argue that they can back up the objectivity of any negative review they post. Fine. Whatever.
There's this strange thing about the Internet where people have been trained that they cannot walk away. They cannot back down. They cannot let things pass without a comment. And it's created a negative, toxic environment under which I think a lot of people don't realize the harm they're doing (and sadly, far too many don't care).
Be BalancedWhat I'm really saying here is before you post a review destroying something that someone else worked very hard to create and put in the world for the sheer purpose of entertaining others? Step back, take a breath, and ask yourself: why are you tearing it apart? What will it accomplish? Is your problem with it based on the simple fact that you, personally, weren't crazy about it? If so, I suggest stepping away.
At very least, try to find something positive to say about anything you review. Maybe you didn't like it, but you can see why someone else might. Be sure to mention that as well. A good (read: well-written) review is not totally negative. It's not just a rant intended to tear something down. It's balanced in all ways.
As a reviewer myself, I stopped posting negative reviews a long time ago. I realized that I'm not holding anyone to a higher standard, because really, what is it about my personal standard that makes it a high standard? All I'm doing is hurting them, and really, what did they ever do to me other than produce a novel, gaming supplement, or film that I didn't enjoy? Yet, my negative words aren't just hurting feelings (if that was it, people just need to cowboy up and get over it) but I'm hurting their actual career. Every single sale I cost them hurts.
In the end--and a lot of people just don't want to admit this about themselves, and I'll wager I get at least one guilty conscience reply here (which will insist it's not such a thing) that vehemently denies it--negative reviews designed to tear down a product are nothing short of cyber bullying, and they're some of the most effective, hurtful forms of cyber bullying there are.
All I'm really asking is that you stop and consider that before the next time you hit "Submit."