[Maul]

I would say that as an author, and considering the new policy and new mechanisms to block addons from loading, one would be wise not to do something that would draw negative attention from Blizzard. At the very least, Blizzard can block your addons from loading. At the very most, include you in some tortious interference of contract lawsuit. Doubtful, but possible, since sites who allow such ads propagate the activity of users breaking their contractual agreement they make with Blizzard by buying the gold though the ad link.

And if Blizzard ever enters into a lawsuit against a company and they get hold of the records of which ad clicks lead to which gold sale, that is not good for the site. This last part is extreme and unlikely, but why open yourself up to Blizzard's possible ire?

I could also see the addon sites like WoWI or Curse removing addons that have websites that support activities that violate the EULA or ToU.

/2 cents