Not sure if this has been covered already, but for my part, a modern poster only looks good if mint.
And an old and historical poster is sort of expected to Come with some historical artifacts.
It is sort of comparable to a modern chair and an antique leather chair. One would buy and try to keep mint, a modern chair. But an antique leather chair with wear and tear, cracked and worn leather, and history is part of its appeal.
Quite what the line is then between old and new, chairs and posters, I couldn't possibly say.