with strip washes, you use the MILDEST dishwashing liquid you can find. Using a nastier one with chemicals, will not help.

Strip washes are usually for wee smells, that type of thing.

Do you have a dog? who likes to play in the basket of nappies just brought in, off the line, (wink).
or maybe "smelling like a wet dog" is how you describe, nappies not being really dry.
it's hard to get stuff dry in winter!

esp natural fibres (cotton, bamboo, hemp). they take the longest to dry. synthetics dry super fast.