Ethics are extremely important in the business world in general, not just entrepreneurship.  Displaying good ethical behavior within the day to day of the business goes a long way in taking those first steps into establishing a successful business.  Practicing bad ethical behavior as an entrepreneur can lead to a myriad of issues, such as multiple negative reviews, lack of investors, and just an overall loss of trust of everyone around you.  I look at ethics the same way I look at integrity.  It is not something that anyone can really take from you, only you can give it away and once you lose it, it is extremely hard to get it back.