Over the past five or six years I've had part in restoring dozens of vintage bikes and refinishing countless parts. A large majority of those bikes and parts were stripped to bare metal and either repainted or re-anodized. While the people I was working with knew very well what they were getting I've not seen those same bikes, frames and parts resold to new owners and on a few occasions the new owners were not notified of the restoration history. While this isn't completely surprising it is rather unsettling.
For a period of time I had all of the frames I restored marked with a Second Spin label underneath the clear on the bottom bracket shell. But it seems even things seemingly obvious like that can be omitted from a description only to be discovered too late. In other cases I've scribed the inside of the head tube or bottom bracket shell, but again those markings may not be discovered easily. More overt marking may be necessary moving forward.
In addition to refinished or restored parts/bike there is a whole new cadre of people completely remanufacturing old parts. Copies of Grafton perches, Ringle cable hangers, IRD seatposts. As far as I can see nobody is marking the parts as replicas and to the untrained eye they are nearly identical to the originals.
Now, more and more I see repainted frames or complete bikes, refinished or replicated parts getting posted up for sale with minimal descriptions and often even passed off as brand new originals to unsuspecting buyers who end paying top dollar for things that end up falling short of the mark.
I would strongly urge anyone who is considering a repair or a refinish first take a second though and reconsider and leave it original, but if that's not an option to take steps to brand or mark the bike or part so that it can't be passed off an original down the road. I wish painters would do this as rule of thumb, but I see the conflict of interest in the desire to get business and keeping customers satisfied. Afterall, it's not the painter's job to keep people honest. I for one plan to do this on 100% of the items that pass through my shop. There will always be people who try to game or profit others and that can't be helped, but those of us who are truly passionate about this hobby need to maintain a degree of integrity that ensures that it continues in a positive light.