When I take a look at some of the details in this case in Florida, one thing that concerns me is the attempt by the feds to set up a situation where there's entrapment. And offer of stolen credit cards as part of the exchange? I would wonder if the $30,000 offered to be exchanged into bitcoin was fake as well, in addition to the flash roll the undercover agent showed the suspect.
In a situation like that, there'd be a good reason to suspect a scam:
"...The US Secret Services Miami Electronic Task Force decided to swing by CraigsList (of course) and localbitcoins.com to see what they could dig up.
Seeing an advertisement that explained the defendant was willing to sell Bitcoin in person for cash, the Feds thought they had uncovered something nefarious. A meeting was set up at the Nespresso Cafe where .40322580 Bitcoins were sold for $500.
A few weeks later a second, similar transaction for $1000 was completed at a Haagen-Dazs ice cream store.
The undercover detective inquired during this meeting if Abner would accept stolen credit cards for payment but Abner did not commit. The final operation took place in a Hotel room (unnamed) for $30,000 – along with wires and surveillance equipment. The detective showed a “flash roll” of bogus cash to Abner, and he got nervous. While Abner did not take possession of the cash, the Feds still busted him and charged him with the aforementioned crimes.
Abner, eventually walked as the case was tossed out by the Judge. Abner and his defense attorneys beat the rap not so much because the evidence against him was tenuous at best but because the Judge decided Bitcoin was not money – as presently defined...."
https://www.crowdfundinsider.com/2016/09/89756-florida-court-explains-bitcoin-not-money/