Selling to shopkeepers would make it too powerful, and wouldn't make much sense because they see goods often.
I imagine that faked goods would be noticeably fake upon VALUEing it, yes, or identical sdescs but different descs.
Ideally I imagine that it would be a value check, and if your skill/roll (does value roll? idk) is low it would show the original object's value, but if it is high enough you get a line similar to 'This is an imitation', and reveal its true price.
Impossible by code standards? Maybe. I've got no idea how code works.