World of Warcraft site has listed a gold-selling FAQ that aims to educate players like Timmy on some of the consequences of purchasing products and services from a gold-selling company.
The site lists the obvious stuff, like spammers and bots, which both annoy people and take up Blizzard resources that could be put to better use, but the article also brings up some things that aren't always mentioned. Much of the gold that these companies trade in comes from hacked accounts, and many accounts are hacked after the owner enlists the aid of a power-leveling service. When the companies have access to the account, the unfortunate victim may also find their personal details being used for identity theft and credit card fraud. The bottom line is, without people using these services, the companies could not continue to operate. We here at Massively are also vehemently opposed to gold-selling, and agree wholeheartedly with Blizzard's message. Just say no, Timmy.