In the time passed since I did my first experiments last year on vintage laundry, I have continued testing on vintage dresses, and so far I have found that with regards to odours there are two major categories. Smells caused by bacteria (such as sweat), and smell caused by mildew and moulds. Of these two the former is by far the easiest to get rid of. In most cases all that is needed is to spray the garment with rubbing alcohol, let it dry, and repeat. Once dry again, wash the garment, and the smell is gone.
Mildew and mould, on the other hand, is more tricky. I first tried to spray the garments in vinegar water (half and half of white vinegar and water), and then launder, but that didn't help. I finally resorted to leaving the garment overnight in vinegar water. I rinsed the garment, and washed it with woolite. I then hung it out in the sun to dry, and now it's fine. But next time I see a smelly dress I really like I'll only get it if the price is right. At the moment I still have 2 more dresses in this category, one of them the dress you see in the below picture. It's made of silk taffeta and covered in hand painted net. This one will have to go to the dry cleaners, I think.