I certainly don't intend to answer for Alain Briot. The OP referenced his guarantee. I've been reading the Briot book on Marketing Fine Art Photography, but I've slept since reading the part about the guarantee so I could be a bit foggy. I believe one of the things Alain guaranteed was that the purchaser would still like the photograph when they got home and displayed it in their home. If not, he would replace it. I think it may be reasonable to offer such a guarantee, but limiting the time the purchaser has to make that choice is also perfectly reasonable. You can't afford to fund a Fine Art Photograph Lending Library. I would think that you guarantee the quality of the materials you use. Not that they might go bad someday, but that you are using the best available and not passing off substandard materials in your art. Then you guarantee that they'll like the art when they get home. And then you're done. Allow them a period of time to appreciate the art in their home and if they just don't like it in that context, they can choose a replacement from your catalog.
How the hell can you guarantee what another person is going to feel?
Surely, that's totally up to them and their native intelligence, lack of which should be their responsibiity. Talk about the concept of a 'nanny state'! Were I to order, buy and take home a blue car, to discover next day that I think silver would look more effective in the driveway, should I expect the dealer to take the thing back and replace it or reimburse me as if it had never left his showroom?
Business ain't charity. An exception would be in the case of a very
goor repeat client, in which case it could be good business.