DENVER (CBS4) – The first clue it was a scam was the caller’s sense of humor.

“We know government has no sense of humor,” Tom Logan said.

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Logan said he received a voice mail on his work phone, presumably from the Internal Revenue Service, in an effort to scam him.

The message left said: “Hi, this call is from IRS, Internal Revenue Service. This message is for you. If you don’t return the call, and if I don’t hear from your attorney, either, then the only thing I can do is wish you good luck.”

Logan said he knew immediately something wasn’t right.

“Yeah, good luck if you don’t answer this call, which is kind of a clue this wasn’t a government agency,” Logan said.

Logan is one of countless Americans targeted with scams like these. He didn’t fall for it, but the attorney general’s office said thousands of Coloradans are conned.

Broadly, the scam informs residents that they haven’t paid taxes. In some cases, lawsuits are threatened.

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The state attorney general’s office is launching an aggressive effort aimed at consumer protection. In 2013, the office received more than 20,000 complaints and questions dealing with fraud.

A public service announcement from the attorney general’s office features a cobra in a suit that asks, “How do you spot a snake oil salesman?” There are also boars and chameleons in suits.

In addition to the spots, the office has created a website — — and catchy advertising campaign to prevent fraud.

“We keep very close track of who complains, who they complain about, and we choose who to investigate and prosecute based on the complaints we receive,” Attorney General John Suthers said.

Suthers’ office says the IRS will never call to ask for back taxes. It’ll send a letter instead.

Residents who feel they’ve been targeted in a scam should head to the website to complete a streamlined process for filing a complaint.

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The website is financed with money the attorney general recovered from scam artists.