Three characteristics of responsible talk are given here. Our talk should be gracious. Our talk should be salty. And our talk should be perceptive. Gracious talk is courteous, cordial, cheerful, controlled, compassionate and Christ-like.
Gracious talk is free from bitterness and bad-mouthing.
Needling a person we work with is not gracious talk. Sour grapes about our grades or our position on the football team or our missed promotion is not gracious talk. In the days before refrigeration, salt was used as a preservative. Meat was impregnated with salt to prevent the spread of decay and corruption. In the same way, our talk with unbelievers should have the effect of preventing or slowing the spread of spiritual and moral decay in this world.