Think about big picture of agreements
When you buy a software product, it would seem that by now, one should know they are going to have to agree to an EULA. I haven't bought any software in the last 5 years that didn't have one.
That said, you should attempt to find a copy of the EULA to read before you buy the software, since, as already mentioned, most places won't refund opened software.
The EULA for WoW was easily obtainable online at http://www.worldofwarcraft.com/legal/eula.html
By purchasing a game you agree to (IMO) use the game as designed by the software company AND to the terms of the EULA. If you don't agree to those terms, don't buy.
FYI - I do play WoW
October 24, 2005