In general, Sun Tzu's Art of War is readily applicable to business in almost all situations. So deception is valid in situations where company secrets are concerned and on competitive grounds. However, deception should never be used on employees, customers, partners, and the community. Why? Because Sun Tzu didn't deceive his own soldiers, ruler, allies, and nation. There may be information that he wouldn't divulge and he might have disagreements with them all, but he acted always in their best interests and never at their detriment. In other words, he did not undermine his very purpose of existence.
So it should not come as a surprise that one should never undermine his or her own family, friends, employees, etc. They, too, are analogous to internal soldiers and allies. We've pointed this out in the five common mistakes people make regarding Sun Tzu's Art of War.