Swan chair, faded Fabric  

It never hurts the price...
It never hurts the price to recover a chair . who wants to sit on a piece of old smelly crap.
That is the wrong way to recover a chair putting new fabric over old. Homemade DIY folks use to do it that way cause they never knew how to take the old off, you have nice chairs do it the right way or don't do it at all.

Huh?
"It never hurts the price to recover a chair"
I'm sorry, but I have to disagree and I think you could find a great many antique dealers, museum curators, and auction house specialists who would also disagree.
I have chairs reupholstered all the time. If the upholstery is horribly dirty, faded, torn, or not original to the chair, you often have little alternative. It matters little with some designs, but with other pieces originality can add significantly to the value.
There are times that the original upholstery can be repaired or restored and there are times that it's worth the extra effort and expense. There also times that the upholstery may be in poor condition, but it still is worth more with the original than having it replaced.
I don't think that you can make a blanket statement like that. I think the answer is more like 'It depends". There are a number of variables: the chair, the fabric, the substructure (webbing, springs, foam, etc).
The OP says that they have a pair of swan chairs. My questions would be: what fabric are they upholstered in and how bad is the fading? Obviously photos would help, and there is a subjective component if they intend to keep them and live with them. But again, I don't think it is as simple a decision as you posit LRF.

Bruce Upholstery
Bruce Upholstery based in London are recommended by Fritz Hansen for both Swan and Egg chairs.
Anne Marie is extremely helpful and will be able to advise. I had a swan done in leather by her. I was told that the chair will invariably end up having to be re-foamed because the fabric is bonded and usually pulls sections of the foam off with it.
It's not cheap and given the expense, new fabric on new foam is probably the most economical when thinking about the longevity.
I can't really see the value of a fabric Swan being that affected by an upholstery job, if it was leather- maybe.
Reupholster it, do it properly, use it and more importantly- enjoy it.

What Pegboard said,
but also--"That is the wrong way to recover a chair putting new fabric over old. Homemade DIY folks use to do it that way cause they never knew how to take the old off"
I've seen more than a few piece done by "professionals" with fabric upholstered right over the old fabric and petrified foam. Not Swan chairs, but still--SO wrong. I also knew an upholsterer who would buy very used sofas at auction and just take the cushions. He said the foam was perfectly good and he used it when reupholstering pieces for customers. So there ya go.
That said, in addition to being a bad idea for obvious reasons, it wouldn't work on a Swan chair because the extra bulk around the handstitched perimeter of the chair would ruin the whole look.
How badly faded is it, anyway? I know some people are comfortable with the effects of aging on their furniture but others really want their things to look as close to perfect as possible--which I can understand with a chair like the Swan.

Here is an instance
...where we went to the trouble and expense to save the original fabric, and I think this chair is more valuable with the original fabric than if we'd had it replaced.
Granted, the fabric was in perfect condition, it only needed to be cleaned. It was the foam that had deteriorated. But remember, it's only original once.
This restoration was also discussed on this thread:
http://www.designaddict.com/design_addict/forums/index.cfm/fuseaction/th...