Oh lordy, will it never stop?
Social media - blogs, Twitter, Facebook, etc. - is a tool. Tools are neutral - they are designed to help, but they can also hurt. You can build with a hammer; you can also kill a person with a hammer. Similarly, you can build with Twitter, or you can use it to kill your career.
Case in point: Alice Hoffman. A reviewer for the Boston Globe gave Hoffman’s new book a negative review. Hoffman responded with a number of rants on Twitter, publishing the reviewer’s phone number and email address (presumably so those who agreed with Hoffman could amplify her rage).
Another case: Alain de Botton. In this instance, he came across the blog of a NYTBR reviewer who had panned his book. And left a screed in the comments section of the blog that culminated thusly:
“I will hate you till the day I die and wish you nothing but ill will in every career move you make. I will be watching with interest and schadenfreude.”
Don’t. Do. This.
It might feel good for about six seconds, but God knows it’s hard enough to get published these days even if you’re an absolute angel - why would you want to complicate your career by being a jerk on top of that? Reviewers are going to say bad things. Some of THEM are, in fact, jerks. But you never EVER counter with asshole-itude. EVER. Because it will backfire. It will magnify. It will find its way to Gawker or New York Magazine, both of which are devoured by publishing people, and you will have effectively ended the authorhood stage of your life and will have to find something else to do with your remaining years.
Preferably as far away from tools as possible.

