Boiling water + disinfectant beats a shower or any other non-lethal cleaning method. The doll should be more hygienic than any human could possibly be.
that plus a few disposable parts and you're in business. It might take some time to convince the health dept, though.
The problem is trust. People won't know for sure that's what they are getting. It's a similar problem with online fresh grocery shopping.
I have a few friends in robotics who periodically pitch this idea around.