If you have no idea what I'm talking about, you can consider yourself lucky, but I'm guessing it's become pretty widespread by now (at first, I'd just chalked it up to being on a high population server). Spammers are almost constantly sending whispers ingame to buy and sell gold and powerlevel characters. Blizzard has of course said that they are banning players who get reported as spammers, but, also like Sniffledoo, I think it's time they went another step-- it's time to go after the sites that are doing it.
As always, IANAL, but clearly we know where these spam messages are coming from-- they are being sponsored by the sites advertised (I can, unfortunately, list a few of them off the top of my head, but I won't link to any of them, because they just don't deserve it). Does Blizzard have a legal claim against these sites for ruining the player experience and consistently breaking the TOS? If they have documented this activity, couldn't they take it to court and at least sue these sites for ruining the game experience?
It's gotten to the point where I would almost be willing to agree to a TOS that says "I agree to be sued for spamming" if it means Blizzard has a better legal footing against these idiots. Reporting these players is the best thing to do right now (even though these are alts that are just created and deleted, maybe even in a matter of minutes), and there are even addons now that will block and report this stuff for us, but why can't Blizzard do more? Why haven't they gone after the sites sponsoring this junk?
Update: A couple of people have already mentioned the gold links on this site-- in case you missed it, we are constantly working to get rid of them. WoW Insider does not condone or endorse any activities that are against the TOS, including powerleveling and gold buying and selling.