well , the situations depicted by you are practical and the concern offered is more hypothetical. sperms on contact with soap an alkalinizer , this breaks their acrosomal head and render them dead/defective. secondly sperms survive in a very delicate environment of nutrients supplied by precum which has fructose, now while bathing this element stands diluted and the survival rate of sperms decrease. so contemplating pregnancy after an oral sex and thereafter washing of sperms to the vagina and penetrating the barrier and entering the uterus , is a long way for the sperm to travel. though their life span is 72hrs provided they are in a protected environment,. regards