I hope you've found a solution. Smells are just a part of everything, but I wouldn't the poo smell in the house, that's for sure.
I've never had that problem (yet!) but I was wondering what shampoo you use? Have you tried a stripping shampoo? That is, one that removes all products from the dogs coat after a build up. I often use these in general on my Lhasa's just to make sure nothing is left in.
Hope you find a solution soon.