Matt from The Forge has an interesting article on how RMT is like prostitution: the secondary crimes surrounding the activity are often worse than the primary activity. From that he concludes that the easiest way to avoid RMT problems is to legalize it. SOE agrees and transfers their Station Exchange to Live Gamer, a company running legal RMT for any game company that wants to legalize it.
Me, I agree that gold spamming and scamming and botting is worse than the gold selling itself. But when I read about the RMT is like Prostitution analogy, the one thing that comes to my mind is the following: RMT is like Prostitution, because everyone blames the sellers, but obviously for every seller there are multiple buyers, which are generally ignored. I'm not saying it is all the buyers fault, but looking at the buyers and understanding their motivation has to be an important part if you want to get rid of the problem. RMT would die if gold farming wasn't both boring and necessary to support "fun" activities.
In WoW, which is by default the biggest RMT market, I have the impression that gold selling is in decline. There is still some gold spam, but less of it. Blizzard apparently is now scanning mails for large sums of gold being sent from one account to another and intercepts those. Even AH mail gets an one hour delay to give GMs the chance to look at suspicious transactions. And Scott Jennings from Broken Toys reports that IGE is imploding.
I noticed that as long as I was playing casually, things like doing daily quests or fishing are extremely profitable. I have two epic flying mounts, and enough gold to buy the epic ground mount for my mage when he hits level 60. Only raiding is extremely expensive. Not just the repair costs and consumables, but the expectation that if you raid you should have all your gear gemmed up and enchanted up to the max. I used mats worth 500 gold just to get one +81 healing enchant on my new raiding mace! You don't need primals if you play casually. So I'm wondering whether the reason that Blizzard never looks at the RMT customers is due to the fact that it is their favorite players. :)