Our answers and responses usually indicate far more than the words we speak. A politician who suddenly becomes upset and even angry at a simple question has just told us a lot about himself. A sarcastic defensive retort tells everyone that there just might be something to the charge. If we're innocent, then there's no need for an emotional response. Good leaders shouldn't be easily provoked, and doing the right thing needs no defense.
Old Testament Scripture gives a good test for discerning truth or lie. The person in question was given bitter dust to eat. If he had been lying, strong physical symptoms would be his dead give away. If he had been truthful, the dust would have no effect. His immune system proved strong enough to withstand the test. The guilty succumb while the innocent are unscathed.
Living with guilt and bitterness soon evidences itself and affects all of our dealings. Jesus said that which enters a man does not defile him, but that which comes out. Whatever we allow in makes its home and will soon produces its fruit, good or bad. No amount of stoic self control will succeed in masking the true self. The damage is done internally and externally.
Paul also gives a humility check. Being quick to critically condemn others only indicates that we are just as guilty. The critical, negative spirit, the cutting words and angry responses only serve to condemn ourselves and prove to others that control is an issue.
Unfortunately even partial guilt can produce the same defensive tendencies. Teflon works best with an unflawed surface. Nothing sticks. Power, influence and health are nice benefits for remaining not guilty. Thanks to the Lord for being the only one who can wipe the slate clean and produce an immune system that enjoys innocense.