To me, shopped means no visible dirt on the playfield in nooks/crannies that are easily cleaned. If I can take off less than three screws to remove something and there's standing dirt grime that wipes away with my finger, someone is full of baloney about shopping it. Another test is pulling off the apron. It's four screws and if you get under there and find it filthy, it isn't shopped.

Dirty troughs are the worst. You put brand new rubber on a machine and brand new balls in it and the machine will be filthy in 20 plays if you don't at least wipe the trough clean under the apron (this is for older machines where the trough mechanism is largely above the PF, of course).