Or, on the contrary, have you ever written a negative review so sarcastic and witty that you're gleefully proud of it?
Lots of questions here.
I often hear the word "fair" bandied around. Reviewers feel that their analyses have to be fair. I appreciate the sentiment, but am not sure it's applied in the way it's intended. The word is often used to mean "balanced," i.e., reviewers should always find something positive to say even when they hated a novel and wanted to fling it across the room. Yet the opposite never holds true. If you truly loved a novel, chances are you won't go out of your way to find something critical to comment on.
To me, the dictionary definition of the word "fair" seems more appropriate - free from bias, dishonesty, injustice. In other words, reviewers should be open-minded and judge a novel based on what it is. There are certainly kind (or kinder) ways to express criticism, I'm not disputing that, and I have no problem with it either. And yes, it can help to assess a novel's appeal to other readers if you find a book's simply not your type. That falls into my definition of "fairness," and is different from its being "balanced." (Though you may quibble.)
For a classic example of how "always say something nice" can be taken to the extreme, check out Philip Hensher's review of James Thackara's The Book of Kings, published in the Guardian's Sunday Observer in September 2000. Ouch! You have to admit it's funny, though (or at least I can). If you felt a novel deserved it, could you picture yourself writing a review like this?
What does the word "fair" mean to you, as a reviewer, as a reader, or even as an author?