You could try rubbing a little bi carb into her coat [as long as it wont aggravate her skin condition] then brush it out, or use some scented wipes on her, though I find that can make some dogs worse lol.
Smell is a typical 'symptom' of a skin infection/allergy....you could maybe try her on some evening primrose oil to soother her skin too. However if you bathe her too often this can have the opposite effect, it will strip her coat of natural oils etc and the ph balance in her skin will go into overdrive to compensate hence she wont smell fresh for long after a bath...its a vicious circle...
Poor old girl - at her age the last thing she probably wants is lots of baths. Ok if its a medical problem but just because she smells? Thats what you have to put up with in return for 16 years of love and loyalty from her. Make the most of it, she won't be around for ever. I have three oldies, soon to be 16, 15 and 14 and two of them wiff a bit now and again.
my 12 yr old shar pei smells, he has a brush hair coat and moults badly, we cant get him in the bath because of his arthritis so we sponge him daily, we love him dearly and accept he cant help it, after all lots of old humans smell too.