PHOENIX -- October's massive hail storm in the Valley left hundreds of millions of dollars in damage and a rich environment for scam artists.

Many homes had damaged roofs, which have yet to be fixed, and the Arizona Insurance Council's Ron Williams is warning people about bogus roofers.

First red flag? Out of state contractors.

"Because you're not going to be able to know if that contractor will be there to follow up on any repairs that might be needed," Williams said.

Other red flags? Repairmen going door-to-door offering needless repairs.

"Someone who pushes you into making very costly temporary repairs, even before they start the regular repairs."

And roofers demanding up-front money.

"They push you into signing over that claims check that you've received from the insurance company. Never hand over that check or sign over that check until the work is completed."

Beware of contractors who offer to waive the insurance deductible, Williams said.

"Usually, what that means is you'll be paying for that deductible on work that is not as professionally done, on materials that are cheaper."

He says it's critical that homeowners do their homework.

"It's important to take the references that they give you, check with the Better Business Bureau and the Arizona Registrar of Contractors."