Thinking of paying someone else to clean up your credit file? Anything they can do, you can do better. And cheaper.

But it takes time and dedication.

If your report contains genuine errors (read: debts that have been on the report beyond the allowable time or debts that really aren't yours, not just debts you wish weren't yours), you can fix that yourself for free. And with a minimum of hassle.

But if the debts really are yours, the creditor can keep them on your report, usually for seven years. And no third party has the magic to make that go away. On the other hand, some for-profit credit repair firms offer a viable option by disputing items you believe to be inaccurate and pursuing the necessary paperwork and follow-up you may not be able or willing to do.

"Anyone who promises to get accurate information less than seven years old off a file is lying," says Gail Hillebrand, senior attorney for Consumers Union.

Some other red flags: companies that contact you, hard-sell tactics, outrageous promises and equally outlandish fees. "The standard line is that if it sounds too good to be true, it probably is," says Chi Chi Wu, staff attorney for the National Consumer Law Center.

Here's a rundown of several of the most popular approaches for separating consumers from their money with the promise of a better credit rating:

Scam No. 1: We have an in with the credit bureaus, speak their language or know some super-secret regulation or handshake that will make them delete the unflattering citations from your file.

What you need to know: There is no such thing. Some companies take the money and run. Others will deluge the credit bureaus with frivolous disputes of the debts in your file, says Linda Sherry, director of national priorities for Consumer Action.

The bureau may list the debt as disputed while it investigates, says Sherry. Debts may disappear during the short investigation (after which they will return), and the company will show this temporary "clean" report to collect its fee, she says.

Or, if the bureau realizes what the company is doing, it may simply ignore what it recognizes as bogus requests, says Joe Ridout, spokesman for Consumer Action.

In addition, the Credit Repair Organizations Act prohibits any company from taking money until after it does what it promised, says Susan Grant, director of the National Fraud Information Center. So if anyone is trying to bypass that federal law (or banking on the fact that you don't know about it) by getting you to send, charge or wire money, that's a bad sign. "The crooks always ask for money upfront," says Grant.

We can convince the creditor that you don't really owe this debt.

What you need to know: This is along the same line as people who claim that the Internal Revenue Service is illegal, or challenge the validity of U.S. currency. The way it works is similar to the previous scam. Con artists will come up with a scheme to have you challenge the debt or will bombard the debt holder with procedural requests that will supposedly make them drop the claim, says Deanne Loonin, staff attorney with the National Consumer Law Center. "Federal agencies have described these schemes as bogus," she says.

"There are times when consumers do have defenses to debt," Loonin says. And that's when it's time to bring in a lawyer.

Scam No. 3: We can get you a new, clean credit file.

What you need to know: Not legally. Some firms will try to get customers to apply for new taxpayer identification or Employer Identification Numbers (also called an EIN) for the purpose of building a new credit history. It's a felony, says Ridout.

But the reason people get taken is that con artists don't explain the whole scheme, so consumers don't realize what they are being asked to do. Consumers also may not know that getting a new number to create a new credit history is illegal. And the whole concept is based on faulty reasoning, says Ridout. Since the new file will list the same name and address, it would still have all the same information and history, even with a new number.

Beware if anyone talks about getting you a new credit file, file segregation or a fresh credit history.

Scam No. 4: We can clean your credit fast and use our contacts to get you a mortgage (or credit card or loan).

What you need to know: This is one of the more recent credit repair scams -- and one of the most costly, says Ridout. Con artists dangle the promise of much-needed money or loans in front of desperate consumers as an incentive to pay, pay and pay. Some scam outfits mimic credit counseling agencies, others imitate mortgage companies, says Ridout. But all they do hit you up for money (sometimes several times) then leave you empty-handed, he says.

And since there are genuine community nonprofit groups that help educate consumers and help with affordable housing issues, scammers may also try to imitate that business model. The best advice: Hold onto your wallet, and be wary of any big promises or fast fixes. Reputable community-based organizations focus on education, and they don't charge hundreds for it, and work with lenders and government agencies you should already know. When in doubt, do a little reference checking on the Internet, with the state regulatory or consumer offices and with local offices of nonprofits and community groups you trust.

Scam No. 5: Call our handy 900-number for details on how to fix your credit.

What you need to know: This is a subscam that can be combined with any of the others. While you are looking for help, the con artists are looking to keep you on the line as long as possible and make money from the per minute charges, says Ridout.

Look out for yourself.

Scammers are often vague on details. If you have trouble defining, understanding or explaining the plan for cleaning your credit, that's a bad sign.

Also, "any offer of guaranteed credit is almost certainly to be a fraud," says Ridout. Ditto quick-fix promises. And beware of nameless, faceless entities. Legitimate counselors will usually want a face-to-face meeting to go over all your financial details and their assistance usually includes some financial education, he says.

Some questions to ask:

• Who is proposing the plan? "A lot of these companies will have a lot of claims against them," says Loonin. Vet anyone before you accept financial information, especially if you have money trouble.

• Has this entity had problems before? Call your state's regulatory or consumer offices to see if there are any complaints or actions against them. Don't forget to check in with the company's home state if it's based elsewhere. And run the business and names of the principals through a couple of search engines to see if there are problems.

• How are they paid, how much and when? Since you can do your own credit repair for free, that's your basis of comparison. If you need a repayment plan or guidance, an organization affiliated with the two main nonprofits, the National Foundation for Credit Counseling and the Association of Independent Consumer Credit Counseling Agencies, can help you for a nominal fee, not hundreds or thousands.

• What's the downside of this plan? Genuine credit counselors are careful to present the positives and negatives behind any plan. Scammers tend to focus on selling the upside.

• Did you contact them or did they contact you? If someone is trying to sell you, that's a sign to put up your guard.

• And, finally, what's the reason for not doing this yourself? "There is nothing they would be able to do that you can't do," says Grant. "They don't have any secret in with the credit bureaus or secret magic wand that you can wave."

Some things are legal but still dangerous.

When it comes to credit repair, sometimes consumers sign on for items that aren't scams -- just costly mistakes. Two examples:

• Refinancing the home to pay off credit cards: If you're tapping equity to pay off credit debt, think again. What you're doing is raising the stakes and risking your home. When you're having money trouble, the smart move is always to keep the mortgage low and pay it first. Never trade unsecured debt (your credit cards) for one backed by an asset (your house). With the former, you might get a few dings in your credit rating. With the latter, you could literally lose your home.

• Paying for copies of your credit report: You're entitled to a free copy of each of your reports annually. Watch out for sites and services that charge for it, or bundle the service of supplying a report with ongoing credit monitoring for a fee, says Wu.

Dana Dratch is a freelance writer based in Atlanta