(NewsUSA) – Sponsored by GAF – It’s the biggest con being played on homeowners, according to the Better Business Bureau’s new Scam Tracker Annual Risk Report.Some guy knocks on your door claiming to have extra roofing material left over from a nearby job, and offers to fix yours for bupkis.And you know what you get for bupkis, right?Invariably, the scammer — who especially loves showing up in areas recovering from major storms — takes the money and runs after doing little or no work."You always try to give people the benefit of the doubt," the Bureau’s Felicia Thompson told a local CBS TV station in Arizona. "Not everybody’s bad, but nowadays you just can’t do that."No, you can’t. And now that you’ve been forewarned about this particular swindle, read on to learn how to choose the right (reputable) contractor to repair or replace your own roof.* Make certain they’re insured. If there’s one thing that’s non-negotiable it’s that the contractor carry insurance for all employees and subcontractors — and provide a copy of their certificate for your inspection."Actually call the insurance carrier to confirm that they are valid," Angie’s List advises.* Run if they suggest this. Did the contractor vying for your business really just claim to be able to handle a storm-related repair, say, without you paying your required insurance deductible? There’s a name for that: insurance fraud, which you want no part of.* Run even faster if they suggest this. While it’s reasonable for contractors to request a modest down payment before work begins — call it "earnest money" — beware if the figure exceeds 20 percent of the bill’s projected total cost. Should they start talking 50 or even 75 percent, though. . ."The red flags of possible fraud are fluttering," the Coalition Against Insurance Fraud’s James Quiggle has warned.* Know your contractor. When it comes to peace of mind, hiring a contractor who’s a member of a reputable roofing manufacturer’s contractor program is helpful. But certification alone may not tell the whole story. GAF, North America’s largest roofing manufacturer, for example, is exceptionally strict about who it designates as its highest-ranking "Master Elite Contractors" — less than 2 percent of roofing contractors have qualified — and you can find one in your area through a quick search on the gaf.com website."We have a full vetting process we go through to determine whether they’re the right contractors to put in our program, like making sure they’re licensed and insured where required, and have a history of installing roofs in the local community," says Jim Slauson, GAF’s vice president of certification program and services.* Communication skills matter. A knowledgeable contractor will present a range of roofing shingle and accessory options by price, style and color. Balking at running through them with you is a bad sign.Oh, and about that Scam Tracker Annual Risk Report. Guess who’s "most susceptible," as the Bureau delicately put it, to home improvement scams in general? Men aged 55-64.Now you’re doubly forewarned.