Quick Credit Fixes Can Be Risky

(The people who provide their credit accounts for such uses get paid a fee ($100-$200) by the firms for each authorization, but don't dole out the account details to the new "name," thus reducing the risk of unwanted charges.)

Stearns charges $450 and up per line of credit, which could add up to 35 points to a credit score. That's in line with prices recently listed on eBay. So, to raise a score from a poor 550 to a respectable 700 might cost about $2,250. Platinum's Anderson says he charges a fixed amount of $3,750, but the fee includes extensive cleanup of incorrect items as well as use of piggybacking.

Those prices may seem steep, but the benefits of an improved credit score can be much larger. Just one percentage point clipped off the cost of a modest $250,000 home loan would yield savings in excess of $43,000 over the life of a 30-year mortgage.

However, the credit-scoring industry is aware of the practice, so it might not be very useful in the end. TransUnion says it doesn't include authorized users in the calculation of scores. And new rating methodologies due to be implemented next year could eliminate their efficacy at the other major firms.

The other method TradeLine uses may be more controversial, but likely longer-lived. Stearns says it involves new users taking on a loan which has already been paid off in its entirety: "Seasoned primary accounts," he calls them. He charges $999 per account, which he claims should lift credit scores by 40 to 45 points within a five-day period.