The hardest part of preventing yourself from becoming the victim of a scammer is recognizing whether an offer or threat is a scam in the first place.

Many people fail to appreciate a seasoned scammer knows what he’s doing. The more confident you are no one can get one over on you, the more susceptible you are to a true professional.

A successful scammer is charismatic, very convincing, and failing all else, knows how to apply pressure and intimidate his target. He’s anticipated your questions and prepared responses–and he’s maybe even prepared to counter some of the well-known techniques recommended to identify a scammer.

That’s why we can’t ever fault someone for falling for these schemes. These people are very good at what they do. And anyway, if it were easy to recognize a scam, no one would be a scammer. There wouldn’t be any profit in it.

But even a brilliant social engineer can’t hide every telltale sign of fraud. At the end of the day, the scammer has to be able to make a financial transaction to receive his prize. And this transaction has to be done in a way that obscures his identity and can’t be reversed.

Basically, a scammer needs his victim to give him cash. Cash leaves no paper trail, can be picked up at anonymous locations, and payment can’t be stopped when the fraud is discovered.

No matter what the scam is or how good the scammer is, they will give themselves away when the time comes to ask a victim to pony up. Not only will he eventually ask you for a form of cash, he’ll probably also tell you it’s the only way you can pay.

Absolutely no trustworthy company or organization does business this way.

The Federal Trade Commission recommends watching for this very ask if you suspect someone who has contacted you for money is trying to trick you.

Just bear in mind it won’t always be paper currency. There are several payment options a scammer might suggest that essentially function the same as paper currency:

• Wiring money
• Sending or providing the number from gift cards, like Amazon, iTunes, Apple (the scammer will usually sell these gift cards to receive a profit)
• Sending or providing the number from prepaid debit cards, like MoneyPak/Green Dot cards, Reloadit cards, or VISA gift cards

Again, keep this in mind: with the exception of small retailers and eateries you’d visit in person, almost no legitimate business deals in cash only (many won’t deal with cash at all). And no illegitimate business will deal in anything else.

No matter how good his “you owe the IRS a ton of money” game is, a scammer blows his entire setup when he has to ask you for cash–especially if it requires you to buy 13 iTunes gift cards at exactly $150 each and call him back to read him all 13 numbers (hahaha, the IRS wants you to do what?).

So ignore the offer, the personality, the threats, and the details. All you need to do to catch a crook is keep an ear out for the dead giveaway: scammers always ask for cash.

Once the caller demands a wire transfer or a VISA gift card, hang up the phone. Don’t argue, don’t reason with the scammer, and don’t let him know you find his demands for cash suspicious (as we’ve already said, top notch scammers know to finesse you and talk themselves out of corners). Don’t even say a word.

Just abruptly hang up the phone and block the number.