Why do people sell old GW games?

I'm a newcomer to Guild Wars but as I understand it you need an access key code to play any of the games. If a new player wants to play the game for the first time and needs to buy the game/code, why do people on amazon, etc. sell used copies of the game when their access key has already been used? I've been going through a lot of entries under "Used" in amazon, and people write stuff like "Everything is in mint condition!... except there's no access code."
I don't understand how that could be useful to anyone. Is there some way of buying just an access code without a campaign?

Sorry if this is a really silly question. :/

You know I've wondered the same thing myself.

I can think of a couple of simple reasons.

1 - they don't know that the code is not reusable.
2 - they're trying to scam people.
3 - maybe they think someone might be interested in the extra bits and pieces that come with the games. The collectors editions have a fair amount of stuff in them which is perhaps of interest to some people.

Marty, those all make sense, but in Amazon's best interest, the seller better not be trying to scam anyone, and Amazon needs to make it very clear about the access code part. The caveat emptor argument doesn't work well with digital products.

Maybe someone lost their install CDs and that's what they want, so that they don't have to do a few GB worth of digital downloads their monthly limit might not allow for?

trouble is people like amazon should make it clear.same thing with steam,if you have poor internet for whatever reason steam is vurtually unuseable. but amazon dont make clear in their reviews that steam is included in the game,hence lots of return to sellers.
if your a casual gamer,you can be caught out by stuff like this. cheers

then the question is: does amazon KNOW that you cant reuse the keys/sell used accounts? (ebay had/has? this same issue).

but yeah if you are just looking for the cds or perhaps the other paper stuff that came with the game then a used copy is better than buying a new one.

- Many people who sell used games are not aware that GW requires a code and is useless without it. Often times the sellers have unknowingly been ripped off by someone else who sold or traded-in the game to them. (The people selling the games are not necessarily the original owner.)
- Some people may want the manuals, etc, that came with the boxed version.
- In particular, Amazon may not be aware of the key-code restrictions of GW and other games.

Not to mention it is against the user agreement to resale any copy of GW.
http://www.guildwars.com/support/legal/termsofuse.php