very broad term if you ask me. Some prefer 100% original and un-restored as it was made. Some want the item to be mint and perfect.
I know with some items it is a big no no if you restore them as most collectors prefer the age patina look - obviously this does not apply to pins (although it might to some).
I myself prefer games that look nice and play well, so repro parts are ok - but then I have them to play (and work on).