You're missing my point. How do you determine whether an item is used or not? If an item comes back to you in seemingly perfect condition but the box has been opened what happens? Back into the new stack or B Grade?
As I say, it wouldn't be that difficult to use an item and test how it clocks and then box it up without it having the appearance of ever being used. End result: item which is used ends up back in the new stock.
Or are you saying ANYTHING returned goes into B Grade...? And that it's just if you determine whether it's used or not which dictates whether a restocking fee is charge?
If the box is opened, it is b-graded! Simples.
Any item being used is easy to spot, seals if present broken being the easiest one.
No seals visual inspection of the hardware it is easy to tell by simply looking for marks on the connectors.
When you insert a CPU into a motherboard, it marks the CPU.
When you insert memory into a motherboard the connectors are marked.
When you insert a graphics card, the connectors are marked as is the blanking plate from the screw.
So for us who make a living of this we can very easily tell what is used and what is not.
Anything showing any sign of usage is b-graded no matter how slight!