I used to review mountain bikes and parts for a magazine on which I was also the owner/publisher. I've sub-edited many a review also. I've also made whopping mistakes in reviews and written quick filler reviews for products that weren't important, according to our preconceptions anyway.

IME, a product gets a badly written review often because the company sending the product has made the reviewer work too hard. If you're going to send a product in for review with no charger, no covering documentation extolling it's virtues or what makes your product special then you'll quite possibly get a poor review because the reviewer has other products to review that did make their life easy. They've got pages to fill and 3000 words to write by Friday.

Not all publications are like that of course but you don't need to make it hard. A review is possibly the best and cheapest way of advertising a product. It's amazing how differently the big companies with media experience approach journalists than those new to the game.