Booking through Thursday
This week's question:

How much do reviews (good and bad) affect your choice of reading? If you see a bad review of a book you wanted to read, do you still read it? If you see a good review of a book you’re sure you won’t like, do you change your mind and give the book a try?

Reviews do have some effect on my reading choices, but I don't rely on them alone.
Nor do I read them religiously — there wouldn't be enough time to read the books if I did. My main sources are the LA Times and the NY Times online (amazing, just amazing), and the NY Review of Books which is delivered and sits in a pile by my bed for slow dipping and holiday reading.
I'll occasionally look at some of the readers' comments on amazon.com — that can be a lot of fun, once you wade through all the reviews that are nine-tenths synopses and one-tenth 'it was a very good book ...'.
A review is no guarantee of a book's chemistry with me, but it's a good starting point.
I buy a lot of books according to my own criteria, and some according to recommendations that may or may not include reviews.
Once I've read a review of a book I'm interested in — good or bad — I'll probably try to gauge any buzz about it among my friends whose tastes I trust. Nowadays, that includes the book blogs I read. Then I'll mull over it in the bookshop, if it's there.
Usually, I'll trust my own instincts about authors I respect. For example, On Chesil Beach, Ian McEwan's latest, is getting mixed reviews that tend towards the negative, but I'll probably buy it anyway. I like him.
I'm not the sort of reader who buys the latest releases. I often come to books several years after most people have read them. Occasionally, if I remember there being a fuss about any particular title I've read, I'll search out the old reviews to see if my opinions and the reviewers' correspond.