You never want anyone you know to use this word when describing you. It can mean a few different things, none of them flattering. First: without conscience or scruples. Second: unnecessarily extreme or difficult. Third: ridiculously unfair or unreasonable. The latter definition is used in the example sentence.
Example: William was not surprised to see the furniture dealership finally go out of business as he and so many other design professionals refused to use them due to their unconscionable business practices.