Things I have learned from my thus far brief stint as a reviewer for Tor.com:
Negative reviewers: likely to remain negative, no matter how many times you tell them they’re a parasite and should remember their manners.
Other reviewers: likely to be turned off by your description of them as parasites, either because they already remember their manners and/or they’re expending a lot of effort on writing reviews in the first place, so the metaphor is doubly insulting. (And if you’re a writer or editor, you already knew both meanings and the etymology for “parasite”. ((Hell, I know it, and I’m stupid.)) )
“Fair and Balanced” review: tends to elicit a reaction of meh. Doesn’t matter if it’s a positive or negative review.
Review from the heart: tends to generate interest. Doesn’t matter if it’s a positive or negative review.
Just like books, reviews can be sloppily written and poorly thought out. But just like books, reviews can be well written and require some amount of effort to be so (though obviously less effort than a book, nevertheless a reviewer that wants to eat enough for the month needs to review a LOT of books).
I would never think of telling Roger Ebert that he need never write a negative review. Why would you think of asking genre reviewers that?
We’re not here to golf-clap for you, because that really would be insulting. We are here to read you, think about your writings, and write about them, in a very meta kind of way. Although perhaps we shouldn’t bother to read you anymore (and that saves us both time).
Anyways, one reviewer doesn’t matter. Two don’t matter. Even many Amazon reviews don’t really matter. To slam every other reviewer is perhaps a nice feeling, but in general I don’t think it’s productive to draw trends from small sample sizes.
Of course, when a whole slew of reviewers across the board don’t like you (or, worse, are thunderously silent), you have other problems.
That’s all I have to say on the matter.