I hadn’t heard much about this until now, but apparently the process of piggybacking to raise your credit score is sending quite a scare through the credit industry. Basically what happens, is someone with a good credit score will add someone with a poor credit history, or none at all, as an authorized user on an account with a good payment record. Normally this is done when parents want to establish credit for their children.
However, lately businesses brokering deals between those with poor credit, and those with outstanding credit have been springing up allowing people to increase their credit drastically in only a month or two. The fees for this are anywhere from $600 to a few thousand depending on how much you need your credit raised. Part of the money goes to the broker, and part of the money goes to the person who is adding the authorized user. This can be good extra money to someone with good credit, but seems somewhat shady.
The reason this has lenders so worried, is that they may be giving good interest rates to people that have good credit scores through this method, but actually have a poor credit history.
There is a good article on this that can be found HERE.