Do Reviews Make a Difference?

I've been a writer for a lot of years. I write because I have to. It's part of me, like my blue eyes and freckles. I love sharing what I write with readers. If they enjoy my books, that's a huge plus for me. Sometimes they enjoy one so much, they'll send me a private email (which I love), or write a review at the online store where they purchased my book.
And sometimes they *don't* like my book and write a not-so-good review.
I'm not saying no one should ever write a bad review. Everyone is entitled to her/his opinion. A book my friend loves may get tossed across the room to splat against the wall from me, or vice versa.
I think a person has to feel strongly about a book to write a review in the first place. But does that one bad review among several good ones make a difference to you as a reader? Will you believe the "this book was so bad" review or the "I loved everything about this book" review? Will you not buy the book, even though you'd planned to, because of a bad review?
I'm a writer, but I'm a reader too. I want to know the author's writing voice before I buy a book. I love the sample feature on the online sites. One click and I get a nice sample of the book on my Kindle in a few seconds. That's especially nice because not all authors post excerpts on their websites. I post the complete first chapter and an excerpt of all my books on my website. If you want a taste of my writing style, it's easy to find.
Readers want to spend their money on a book that will give them a few hours of reading pleasure. Will you take a chance on a new author if the excerpt/sample sounds good, even though someone put up a one-star review at your favorite online store? Do you only pay attention to books with four- and five-star reviews? How important are good reviews to you?
Lynn