You know what gripes my goat?
When people take public domain materials, clean them up in some non-transformative way, and claim that is sufficient to produce a new copyright (when that kind of work is clearly "Sweat of the brow" work and not "creative work" and is therefore not eligible for copyright protection.)
I don't mind people selling public domain works, or claiming copyright on actual transformations.
But don't CC-BY-NC your restoration as if that's enforceable.