A second-hand article may be accompanied by a story told by the previous owner. This narrative does not amount to a documented provenance. The commercial description should distinguish what is verifiable from what is reported, avoiding conclusions based only on the plausibility of the story.
I propose that we keep the relevant documents and indicate which aspects are not known. The examination of authenticity requires appropriate skills and methods; an accessory present or a package should not be treated automatically as sufficient evidence. Commercial responsibilities must be managed within the applicable framework.
We imagine a product with a receipt that does not allow it to be uniquely linked to the article. The document offers information, but the link remains to be verified. A prudent description avoids turning a partial element into a certainty about the history of the good.
The quality of the offer also depends on the readability of the limits. The client should be able to understand what has been checked and what information is missing. Provenance adds value when supported by relevant elements and is communicated with a degree of certainty consistent with the verifications carried out.