Its a long winded situation, but long story short:
Theres alot of controvery regarding guildwars, as you dont have to pay for it, people concider it as a normal game - that you 'can' cheat on.
But as Chupin said, it does break the EULA, an exploit in the game is obviously against the rules, because you have a method of infinite gain from which others do not benefit.
But as i said - never ending convo, read the EULA for more information
Cheating is wrong, yeah you can cheat at normal games.......so what...there offline, and most people cheat because there stuck, or for fun...but using exploits and bugs to profit on online games is unfair to others.
Such is buying game credits :/