UPDATE: Well, the comforter smells great- thanks to 3 washings (2 in cold, 1 with a white vinegar soak and finally, the thing that did the trick- 1 hot water wash with lots of bleach). I figure even if it falls to pieces in a month- I got at least some additional use from it!
I found (in the depths of the river house) a down comforter and cover that would now actually be perfect (I think....) in our guest room. What's the problem you ask? They smell a wee bit....er...well.. musty. My parents are coming for Mother's Day and I'm itchy for a change in their room.
So, I Googled "how to clean your down comforter" and found that for every person who said that you shouldn't ever wash it about 3 people who said it works great just to throw them in the washing machine and then dry them with a tennis ball to fluff the down.
I'll get back to you and let you know how that goes- wish me luck!