How to respond to bad reviews.

Ignore them. It's as easy as that. But, funnily enough, not everyone does.
Julie Halpern is a writer of YA books. I'd never heard of her before this week, when a blogging, twittering storm blew up because she wrote a foot-stamping, tantrumy, Violet Elizabath Bott of a response to a negative review that she found on the internet.
Ms Halpern has now taken down her post, and the equally cringe-worthy 'poor little me' ones that followed. But you can read the original review here and the responses were all about how the author had poured her heart and sould and time into her work, while the blogger had just dashed off a piece of snark, and the author was in a higher place than the reviewer and no one should write negative reviews at all, because it might but readers off, and authors have feeling too, and google should create a negative review filter (I think she was employing hyperbole at some points, but the general hysterical nature of the thing made it hard to tell).
It's blindingly obvious to most of  us, I hope, that  if an author thinks a review is unfair, offensive, wrong, sloppy or whatever, she should not take it personally, and should absolutely not attack the reviewer in public. Find someone to moan to who knows you are not an egotisical brat -  or who knows that you are an egotisical brat, but loves you anyway.
If you absolutely have to contact the reviewer, be humble. Thank her for spending time reading and reviewing your books, point out nicely that she's got the main character's name wrong, or misunderstood the central metaphor, or given a whacking great spoiler, say how much her good opinion matters to you.  But truly  it's best to maintain a certain authorly distance at these painful moments.
A lot of people have told Ms Halpern this, and maybe she will now spend a lifetime lying awake in darkened rooms asking herself why...why....?
But I have a further criticism of her rant.
The reviewer didn't like her fake kidnap plotline - ('Can I just say – uhhh. The entire Penny debacle was kinda ridiculous.') Ms Halpern was shocked that anyone could doubt the premise because it had actually happened to a friend of hers  ('Ugh! I didn't make it up, beyotch! I had a friend who faked her own kidnapping! Grrrr.').
I've heard this defence before. I asked a writer about the baffling relationship of two people in her otherwise delightful book, and why on earth they didn't divorce -  to be told that they were based on two people she actually knew and were therefore, well, true to life.  I felt short-changed, and was none the wiser. A tiny hint at sexual obsession or financial complexity would have worked far better,
Writers, it is not enough to base your characters and plots on real life and real people. You have to make them plausible to your reader.They are reading a work of fiction, not a memoir or a piece of journalism.
Quite often I've had things happen to me that I regretfully realise would not work in a piece of fiction, because the coincidence is too unlikely or the story is almost too neat. It's fine to use real life events and people as inspiration, but it's not a justification or a defence when people don't believe it.
Early on, I had a review for When I Was Joe which doubted that anything so extreme could happen in the UK ('From the onset it is particularly difficult to accept that the initial event really justifies the extreme of witness protection and this makes the attempt to create a sense of urgency and danger rather tenuous.')  and went on to criticise the characters as obnoxious and unlikeable. For that reader, I'd failed to make the situation feel believable and I hadn't managed to connect wth their emotions either. That was my failing. Their opinion was perfectly valid. Luckily, not many other readers seem to feel the same way, but I try to take the view that I can learn as much, if not more, from negative reviews than from positive ones.
Not that I like them, of course.  Bring on that negative review Google filter.