She may have a perfect complexion, her pick of Hollywood hunks and homes in chic neighborhoods on each coast. But odds are, J.Lo's credit stinks.

Credit scoring is one of the few areas where Madonna, Mel, Snoop, and Demi can't hold a candle to my childhood baby sitter, Mrs. Hayes, in Lawrence, Kan.

Consumer credit scoring models -- developed by the likes of Equifax, Experian, TransUnion, and Fair Isaac & Co. (FICO) -- are simply not equipped to adequately judge the super-rich. These fiscally blessed souls have complicated financial lives that include multiple mortgages, even more cars, million-dollar paychecks and lines of credit that make Midas look like a cheapskate. Even if they balance their checkbooks to the penny and pay every bill the moment the butler delivers it to their bedside on a silver tray, their out-of-the-ordinary finances tend to make the credit scoring system scream tilt.

If there is a clearer sign of the existence of a higher being, I don't know what it is.

American idle
In the eyes of the lending industry's most famous grader (Fair Isaac & Co.), a perfect credit score (that three-digit credit GPA based on your borrowing and bill-paying history) is 850 (on a scale of 300-850). That score is based on one's aptitude in five key areas: past payment history, amounts owed, length of credit history, amount of new credit, and types of credit.

At myFico.com, you can peer into the average American's private financial affairs, where you'll learn that the typical consumer has 11 credit obligations on record; that fewer than four out of 10 have ever paid a bill 30 days or more late; that almost half carry credit card debts less than $1,000, but that 10% have $10,000 or more on plastic; and that the majority of us have had just one inquiry into our credit record in the past year. (Do you even know how you rate?)

With a credit history like that, it's no wonder that the average American's credit score is 678 according to a March poll by Experian. Eh.

How to be a "10"
Who's perfect? According to Fair, Isaac, not too many people. Approximately 11% of the population has a FICO score of 800 or higher, with just 1% or so achieving enlightened 850.

So how do you beat the pants off the curve (and Kevin Costner)? Industry insiders offer the following profile of the perfect credit pinup. Star borrowers have:

  • Between four and six revolving accounts (meaning credit cards).
  • At least one "installment" tradeline (e.g. a mortgage or auto loan) in good standing.
  • A few accounts around 20 years old and a long history of positive use. (To get into the 800 FICO range, 10 years of positive account history.)
  • Been using credit for at least 30 years.
  • No late payments (or other account blunders) for at least the past seven years.
  • Very few credit inquiries (e.g. no more than one to three in a six-month period).
  • No derogatory notations -- collections, bankruptcies, jaywalking tickets (kidding on that last one).
  • Debt levels on credit accounts of less than 35% of their overall credit limit.

A few final tips for those with good credit who want to see a spike in their score. If you happen to misplace the mortgage, utility, or Visa bill or it arrives after you've left for vacation, call your lender and talk your way out of a late-payment notation. Any blemishes in the past two years can put a damper on your credit GPA.

If you put the bulk of your purchases on a credit card (or charge card, such as American Express) and are entering into a loan situation in the next six months, give your cards a rest. Although credit scoring agencies cannot verify this tactic, keeping a zero-dollar balance on your cards for several months reportedly raises your credit score, even if you typically pay off your balances in full. (All charging activity appears on your credit report.)

It might be worth it to forgo the airline miles or cash back you get from charging and instead use your debit card, especially if it means lopping a percentage point or two from a loan or home refinance.

But if you're out to dinner with Jennifer Lopez and feeling generous, go ahead and put the dinner tab on your credit card. J.Lo's credit score probably could use the boost.

Curious about your credit? TrueCredit -- the consumer arm of TransUnion -- has extended Fool readers a limited-time special offer. Receive a $10 discount on its 3-Report/3-Score package, which includes data from the three major credit bureaus (TransUnion, Equifax, and Experian) as well as credit scores (your GPA of borrowing) from all three entities. Fools pay just $34.95.