I usually scan with the lid up as well. (Epson perfection 2400)
With fairly low light I get the black background, and the scanner doesn't hide anything. More light I still get detail, but with a reddish background - if the lamp is close enough it shows clearly in the scan from about 2ft above the scanner.
I also typically scan at 300 dpi, sometimes higher.
I have noticed that the boards auto resize will hide details.
This card has a light crease that's most noticeable right between his eyes. It's clear on the original 300dpi scan, but invisible on the resized one.
I think Ebay also resizes if they're hosting the photos? When I was selling I only used one photo hosted by ebay but included at least two that I hosted myself so I could have nice clear pics. Later when they added the ability to check off that pictures were in the description and automatically used one for the gallery view I just hosted them all myself.
Steve B