Rise of the Creditworthinessmonger

Interesting.

Only a low credit score stood between Alipio Estruch and a mortgage to buy a $449,000 Spanish-style house in Weston, Fla., a few miles west of Fort Lauderdale.

Instead of spending several years repairing his credit rating, which he said was marred by two forgotten cell phone bills and identity theft, the 37-year-old real estate agent paid $1,800 to an Internet-based company to bump up his score almost overnight.

Even more interesting is the fact that the company's methods aren't as shady as you might expect (though it's not immediately clear that this doesn't constitute fraud, or at least a contract breach).

Instantcreditbuilders.com, or ICB, helped Estruch boost his score by arranging for him to be added as an authorized user on several credit cards of people with stellar credit who were paid to allow this coattailing. Parents also use this practice when they add their children to their credit cards to help them build solid credit.

The pitch to those who are essentially renting their credit history for pay is seductive: You don't need to worry about users of this service receiving duplicate copies of your credit cards, account numbers or any of your personal information. It's essentially free money, they are told.
...
Lenders are worried, however, that they're taking on greater default risks by unknowingly offering lower interest rates than they otherwise would to applicants who artificially boost their credit scores. Their trade group has complained to the Federal Trade Commission and is talking with the credit reporting bureaus in case the practice becomes more widespread.

Assuming there's no legal transgression to be read into it, I can still see credit card issuers simply canceling cardmembers' accounts if and when they learn those cardmembers are allowing piggybacking by people with whom they have no relationship other than financial remuneration.  There's got to be some kind of catch-all in the credit agreement that allows them to boot you (and ding you with some long-lasting black mark on your credit report) if they uncover what they deem to be bad faith usage.

A clever idea, anyway.  And it seems to work.

Estruch paid $1,800 in December for three credit card spots, and by January, his FICO score jumped from 550 to 715. In mid-March, he closed on his four-bedroom beige stucco house after obtaining a 30-year fixed-rate mortgage from a unit of American Home Mortgage Investment Corp. It carried a 7.5 percent interest rate and required no down payment.