I hate stinky nappies ! We find that it is only when DD is teething that it becomes a big problem but does happen at other times as well. If all of her nappies are smelly I do a strip wash (hot with double rinse and a little bit of washing liquid) Our normal washing routine is to do a rinse, then a wash with half a cap of purity and extra rinse and either line dry or dryer dry.

oh we also soak in cold water which is good for getting the smell out of the fitteds in our nappy buckets at all times

Hemp is our biggest culprit and fitteds are worse then pockets etc. not sure why