Sounds like you have a fair way to go in regards to teaching her to get her hair wet. Does she have fun at the pool? Swim classes are good for teaching them gently to get their head wet.

BTW, I don't think you or she is disgusting at all. In fact, the hair wash screaming is not a small part of why our family is shampoo free. Mine don't mind getting their hair wet with water though, so they get a rinse in the shower or bath most nights. I ran out of shampoo around last October and it has been fine (except one unfortunate incident of lip gloss though the toddlers hair at christmas time but gran had some shampoo with her).