Updated

No sooner had floodwaters receded and high winds from Superstorm Sandy faded, but another threat arose with the inevitable appearance of the scammer and the con man.

Authorities warn of the likelihood of Sandy-related fraud reaching far beyond the storm zone — from bogus charities seeking donations, to home repair scams and sales of flood-damaged vehicles.

State attorneys general, business and consumer groups and the Justice Department are among those cautioning consumers to be wary as requests for donations start arriving via email, text message, telephone and Twitter.

The bottom line: Maintain a healthy skepticism when pitched by solicitors, contractors and groups you don't know, and give your money to charities and businesses you have reason to trust.

"Fraud is an unfortunate reality in post-disaster environments," said Joe Wehrle, president of the National Insurance Crime Bureau, a nonprofit group which deals with vehicle sales and repairs fraud. "As the initial recovery from Hurricane Sandy begins, there are people right now who are planning to converge on the affected areas in order to scam disaster victims out of their money."

Scams operate from a distance, too. Evidence of the potential for fraud began surfacing online even before Sandy roared through the mid-Atlantic and the Northeast.

Nearly 1,100 Internet addresses related to Sandy have been registered since last Friday, according to Internet domain research site DomainTools. The names reference Sandy and words such as "hurricane," ''frankenstorm," ''aid" and "relief."

Not all such sites are malicious, and some are just set up to get random hits and exposure for their linked advertisements, said Johannes Ullrich, chief research officer for the Sans Institute's Internet Storm Center in Bethesda, Md. But in past disasters, some also have duped unwitting consumers out of money.

Some sites typically have featured a "donate" button. But either the money will never go to the relief fund or they will simply keep your credit card number to use later.

Consumers can vastly improve their chances of avoiding scams by doing a little research and following some basic tips from a variety of sources before opening their wallets.

CHARITY SCAMS

— Be extremely wary of phone calls seeking aid contributions. Hang up on any call using high-pressure tactics to request an immediate donation.

— Watch for warning signs that an appeal might be a scam. These include an organization with a name similar to that of a widely known charity, a caller who's unable to answer questions, or one who offers a prize in exchange for a donation. More details at the Federal Trade Commission site http://www.ftc.gov/bcp/edu/microsites/charityfraud .

— Never send cash. You can't be sure it will get to the organization.

— Avoid clicking on links or opening attachments contained within aid-related spam, even if they claim to contain pictures of damage caused by the storm. The attachments could be viruses.

— Evaluate a charity carefully before giving to it. Vet them via the Better Business Bureau's Wise Giving Bureau (http://www.give.org ); the Foundation Center (http://foundationcenter.org ), a New York-based authority on philanthropy; or Charity Navigator (http://www.CharityNavigator.org ), an independent nonprofit organization that evaluates charity groups based on effectiveness and financial stability.

HOME REPAIRS FRAUD

— Be especially wary about hiring someone who shows up at your door offering unsolicited home repairs.

— Don't hire a contractor who says he's supported by the government. The Federal Emergency Management Agency does not endorse individual contractors.

— Check a contractor's credentials with the Better Business Bureau or state attorney general's office.

— Deal with reputable contractors in your community.

— Have a written, detailed contract that clearly states everything the contractor will do, with estimated start completion date.

FLOOD-DAMAGED CARS SCAMS

— Run a check on the vehicle identification number (VIN) of any used car or truck you consider buying in the months ahead to see if it has been reported to have been damaged. If it has, don't buy it.

Three free services for consumers to check it are offered by the National Insurance Crime Bureau (http://www.ncib.org ), Carfax (http://www.carfax.com/flood ) and AutoCheck (http://www.autocheck.com/storm ).