What determines if an item is "not as described"?
An item is not as described if it is materially different from what the seller described in the listing for that item. This includes for example
You received a different item or different version.
The condition of the item is wrong. For example, the listing said "new" and the item has clearly been used.
The item is missing parts or components (e.g. camera kit was supposed to include a tripod, but you didn't receive it).
The item was defective during first use (e.g., HDTV did not turn on).
The item is a counterfeit.
The item is missing major parts or features, and this was not disclosed in the listing.
The item was damaged during postage.
If the item was accurately described but you no longer want it, this is not covered by the eBay Money Back Guarantee. However, most business sellers still offer returns policies and allow items to be returned for a refund or replacement if you change your mind soon after the purchase (See "I received the correct item, but I changed my mind and don't want it any more – what should I do?")