Indeed, if you use a spermicidal foam for contraception, a douche can wash it away leaving you unprotected. Some vaginal discharge is normal and may vary in color as hormone levels vary. Odors, if any, probably originate from the external genitals. If an unusual odor, a discharge, itching or other discomfort leads you to suspect an infection, see your doctor rather than trying to cure the condition with a douche. And do not douche before you see your doctor.
American women spend millions of dollars a year on douching products.
But, there is no real reason to do so. Regular bathing is all that is necessary.