I am an Amazon Affiliate. That means that if you click on most of the Amazon links on this blog (First Wildcard requires me to use their links) and purchase something from Amazon before leaving their site, I get a small commission.
Sometimes I review products. Unless stated otherwise, I received a free sample for the purposes of review.
When offered products for review, I try not to accept products I do not think I will like. When writing a review, I try to say something positive about a product, even if I do not like it, with the idea of trying to help it find the appropriate market (even if I am not it). However, my reviews are honest, and will state what I do not like. I may just run promotional material in lieu of writing a review, if I don't like a product. I wrote this post about negative reviews. It should give you some idea about how likely a negative review is if I don't like a book.
I review a lot of books from NetGalley, a service that provides digital review copies to "professional readers". Generally if I do not like a NetGalley or choose not to finish it, I will write a 2-3 line review stating why I do not like it and will publish that review only on NetGalley. A sample of this type of review: DNF, plot was way too slow and I never connected with the characters.
Sometimes I will choose t write a negative review, as noted in the prior paragraph.