Originally Posted by
BeenBurned 
They aren't allowed on ebay because they're considered to be "items that encourage infringement." Sellers of fakes might buy them along with tissue and boxes and use the props to "prove" authenticity of fakes.
http://pages.ebay.com/help/policies/...cessories.html
From the policy:
If the manufacturer doesn't offer the accessories or other extras as a separate purchase, those items can't be listed on eBay without the accompanying branded product.
Hangtags and checkbook holders aren't covered AFAIK. Things like dustbags, wrapping paper, etc are now covered under Ebay's Prohibited Accessories Policy - see the link in the BeenBurned post.
The whole Policy explanation says
Policy overview
Some brand name products come with accessories, a warranty, or protective packaging as part of the purchase. For example, a watch may be packaged in a custom box and may come with the manufacturer's warranty.
If the manufacturer doesn't offer the accessories or other extras as a separate purchase, those items can't be listed on eBay without the accompanying branded product. See our guidelines below for examples of items that can and can't be listed on eBay...
What are the guidelines?
Here are some examples of items that can and can't be listed on eBay:
pics.ebaystatic.com/aw/pics/icons/iconRestricted_25x25.gif
Restricted
- Vintage accessories that are generally considered collectible items are allowed, as long as the year the item was made is included in the title, either immediately before or after the word "vintage". Examples include empty vintage boxes, pouches, or tins.
pics.ebaystatic.com/aw/pics/icons/iconNotAllowed_25x25.gif
Not allowed
- Accessories or packaging without the accompanying product. Examples include:
- Dust bags
- Plastic tags (including a tag with a serial number)
- Ribbons
- Tissue paper
- Box for a branded watch without the accompanying watch
- Empty jewelry pouch, tin, or other container that may be used to hold and sell a similar or identical product
- Warranty or certificate (blank, valid, or expired) without the accompanying product