Most people haven’t got a clue about this fact. Probably that's why over 90% of women experience vaginal discomfort (according to our market research).
Your skin produces sebum to protect itself. It makes your skin waterproof and resistant to microorganisms that can cause infections. Sebum prevents soap from drying out to that point where significant health concerns can arise. But soap does dissolves the sebum to some point so you should use soap sparingly on your body.
Your vagina opening does not produce sebum. The labia do contain some sebaceous glands but not enough to keep the vagina healthy if regularly washed with soap. The top of the penis does not produce sebum either and should not be washed with soap.
What can happen is that your vagina gets more prone to infections and chronic inflammation. The best way to wash her is with vegetable oil. Oil cleanses, nurtures and prevents your vagina from drying out.