Uniques Items with skill gems in them... possible trading scam

Unique Items with skill gems in them such as Corpsewade, that has the skill Decompose (1-20).
The level of the Decompose can be seen on the unique item when hovering it, but while trading that skill gem level is fully hidden. This could lead to situations where people could scam others, and sell an item with a high-level skill gem but put in the same item with a low-level skill gem instead.

I hope this makes sense, I would put in pictures, but I'm not really sure how.

Cheers!