One tried-and-true scam which has existed for years in the poker community involves PayPal chargebacks.

It goes as follows:

1) Scammer asks victim to trade cash for PayPal. Sometimes there is extra money involved in the offer, such as "$1100 PayPal for $1000 cash", in order to entice the victim to do it.

2) Scammer offers to send the PayPal money first, and does so.

3) Victim sees the money has been received at their PayPal account, and gives the scammer cash.

4) A week later, scammer calls PayPal, claims it was a fraudulent charge, and PayPal reverses it.

Unfortunately, this is more effective than you might think. You can call PayPal and complain, and they might close the scammer's account, but they will rarely refund your money. This is because there is no protection built into the "friends and family" (no fee) transfers, so PayPal doesn't give a shit. In fact, PayPal usually defers to the scammer's bank for guidance. If the scammer claims "fraud" to his bank, and the bank believes him (which they usually do without much investigation), the bank labels it as fraud, and PayPal trusts that determination.

Presumably, this is because the bank actually takes the money from PayPal, so the only way they can recover it is to take it from either the scammer or the victim. If the scammer's account is empty (which is almost always is), they take it from the victim.

Anyway, this allegedly happened recently, as poker pro Jessica Dawley claims that fairly unknown player John Lee pulled this scam on her.