There are alot of sellers on Ebay selling fake cds, cd-roms dvds etc. Not only does it violate Ebay rules but it is against the law to sell or own one unless you have the original.
Most sellers get around this by saying it is a back-up disc or it comes with full art work, but it is still a copy!
To know whether it is a copy or not you should click the "ask a seller a question link" (found on the right hand side of the auction listing) most sellers will reply, if they don't then it most probably is a copy. If you are not happy with the response they give you then do not buy!
Some listings say "please contact me before bidding", "this comes with full artwork, just like in the shops" or "a real bargain comes with full track listings" etc etc These are definetly copies & should be avoided like the plague.
Also always check feedback even if it 100% because they may have neutral feedback which doesnt affect your rating & sometimes you can get the jist of what they are selling from the feedback they have received.
Generally though if it is an original most sellers will put this in their listing eg "This is an original, i do not sell copies".
Most of all if when you receive your chosen cd,dvd etc & it is a copy do not be afraid to message or email your seller to tell them you are NOT happy & you want a refund, most will refund you in fear of being reported to Ebay if they do not. If they refuse to refund you then start an item received not as described found in My Ebay on the left hand side, this will go to paypal who 9 times out of 10 will refund you. Then it is up to you whether you report them to Ebay for violating Ebay policy or trading standards.
I hope this helps some people out there & if in doubt please get in touch with me & i will help you the best i can.