There's a darker edge to the salvage trade, and it's worth naming: architectural theft. Ornament, hardware, mantels, even whole fixtures have been stripped from empty houses, unguarded sites, and buildings nobody had a right to touch, and because old parts change hands fast and out of sight, stolen material can move through the trade without a trace. Most salvage is honest. Some isn't, and the honest part of the trade has to reckon with that.
An object can't prove itself
The core difficulty is provenance, and it's structural. A salvaged fixture carries no certificate of its own past. It doesn't show whether it was recovered legitimately or stripped without permission, because the object looks the same either way. So the difference that matters most, how a piece was obtained, is exactly the thing you can't read off the piece.
What a dealer can honestly offer
That's why provenance, in the strict sense of a documented history for each object, is a promise no honest dealer can make for most salvage. What can be offered is different: sourcing from trusted channels, attention to where material comes from, awareness of theft alerts and stolen-property reports, and a willingness to talk plainly about how pieces were recovered. Reputable trade bodies circulate alerts about stolen architectural material, and responsible dealers watch them and steer clear of anything that surfaces on such lists.
Salvager's Note: No one can certify most salvage's full history, so treat a promised "documented provenance" on ordinary pieces with skepticism. What you can reasonably expect is a dealer who sources responsibly, watches stolen-property alerts, and talks about it openly.