A Discourse on the Sallekha Sutta
Wrong livelihood is to earn one’s living by obtaining money improperly.³ Some people commit unwholesome deeds such as killing to make their living. However, some commit unwholesome deeds not for economic reasons, but because of their greed or anger. Unwholesome deeds that have nothing to do with one’s living, but stem from anger or greed are not wrong livelihood, but wrong action or wrong speech. For example, the killing of mosquitoes, snakes, etc., or one’s enemy through anger is wrong action. However, the killing of chickens, pigs, fish, etc., for the market or for one’s own consumption is wrong livelihood. As for stealing or robbing, it is usually done for economic reason and so most of these acts are to be classified as wrong livelihood. Stealing out of malice or through ill-will, habit or propensity is, of course, wrong action. Illicit sexual intercourse has usually nothing to do with one’s living. To seduce a woman, however, for the sake of money or for one’s living is wrong livelihood.
Telling a lie in a business transaction is wrong livelihood; but if you lie for another reason, it is wrong speech. The same may be said of slander. Nowadays some kinds of propaganda are defamation that fall within the category of wrong livelihood. They are very harmful. Abusive language is not often used in business. However, there are many kinds of wrong livelihood in the form of idle chatter that we can find in fiction-writing, play acting, film-making and so forth.
All kinds of wrong livelihood involve violation of the moral code that prescribes abstinence from killing, etc. Those who observe the five precepts are free from the seven kinds of wrong livelihood that we have mentioned about. It is obvious that those who adhere to the eight precepts with right livelihood as the eighth are especially free from wrong livelihood. Right livelihood is to earn money lawfully with moral life untainted by any kind of wrong livelihood.
Source:
http://www.aimwell.org/Books/Mahasi/Sallekha/WrongThought/wrongthought.html