Most disputes in the art trade are not disputes about taste. They are disputes about paper: who owned the work before, what was repaired and when, and whether the figure someone was quoted had anything behind it.
So the house works the other way round. A work is catalogued the day it arrives and given an inventory number that stays with it for life — on the condition report, on the valuation, on the invoice, and on every notice sent while it is in transit. Ownership history is written down and shown to the buyer before money is discussed, not after.
Where evidence is thin, it is described as thin. A gap in a provenance chain is stated plainly rather than smoothed over, because a buyer who discovers the gap later has been sold something other than the work.