Sun Tzu said: All warfare is based on deception... Hence, when able to attack, we must seem unable; when using our forces, we must seem inactive; when we are near, we must make the enemy believe we are far away; when far away, we must make him believe we are near.
Sales is warfare. Therefore all sales is based on deception!
In all this you need to define the enemy. The enemy is not the customer... it is your competitors and those who are to win big in case you lose. These are the ones you need to deceive while committing your resources to win a deal.
Thus, All sales is based on deception... Don't you ever forget that...