Well, the dealership had some people go out and check, and they don't think they can sort it without taking the ducts and all apart. They've no idea at this time where the smell is coming from.
What I'm going to do is install that Frescious filter I just bought after running it for a while with no filter (in case something got on the stock filter), try about fifteen minutes of ozone (do NOT run that stuff long; it eats polymers) and see if that helps. That will remove some diagnostic issues. If I can't get it gone I'll have to let them take it apart; but they told me it would be a good idea to call Volkswagen directly, tell them where I bought it, and see about... Whatever he told me to ask. I forgot, but I'll ask again when I get down there.
This car is dead to me if that smell doesn't disappear completely. I will not drive it, nor will I own it. It smells like it's worth about $200 now. As of this time, so far as my mind is concerned, it no longer feels like my car.
I feel like I've borrowed it; not bought it.