It's not always as clear cut as that. We know the human heart is deceitful and desperately sick. If we are angry, envious, bitter or any other of these to a brother and say or think something sinful, we have sinned. This is not always a deliberate sin, but a sin all the same. A person that can truly control every thought and action and know how God views every one of them, is a very special one at that. Our discernment is a pretty shallow assessment I feel.
In regards to healing, a person living a completely righteous and sin free life still does not merit healing on demand. if it is Gods will to heal, then thus it will be; if not, no - it's Gods decision. So when I pray for family that have serious conditions, my prayers are heard, but it is Gods will, not mine that decides.