Why would a Person Cleanse themself before Ritual:
A Person in the craft should cleanse themself before a ritual for many reasons. When you cleanse your self you remove negative energy, Negative Emotions, Daily Problems, fear and other negative energies. Another reason you would do this is to show respect to you God and Goddess.
Why Would a Person Cleanse themself before a Spell:
A person in the craft should cleanse themself before a spell to pervent negative energy from going into you spell removing bad intentions. A Spell is like a prayer which is active, You would also be respecting the God and Goddess.