I'm a book hoarder. I like to keep all the books I buy. I reread my favorites at least once a year (LOTR, Harry Potter, The Dresden Files will be added to this list as soon as I get caught up on the series
).
I've always bought books based on a mix of reviews, recommendations and the description. I've been lucky and haven't bought many books that I didn't enjoy enough to finish. It has happened, but rarely. Also, if it's the next book in a series I'm reading I don't read reviews, I just buy it. If it turns out to be awful I won't buy the next one.
I try not to rely solely on reviews, different people have different tastes. I'll read a couple 5 star reviews and then read a couple 1-2 star reviews.