An HUO pin could have been left near a window and be faded.
An HUO pin could also have had the snot played out of it, never had the balls changed, and suffered PF wear. Similarly, it could have been stored in a non-climate controlled environment and be rusty, etc.
An HUO pin could also have been routed and be misrepresented by an unscrupulous seller with the receipt.
Listing a pin as CQ can invite heavy scrutiny to your listing (unless it looks like it just slid out of the box and has zero defects--if it has a few, Just-Under CQ might be a more accurate description).
Just list it as extremely nice or some such wording (if it truly is) and let the buyers decided for themselves what classification it deserves.