What's the catch?

wp746911 said:   covered before-having trouble finding old threads. From what I remember, it's a combination of people paying more for them to launder money, and/or people receiving them then not paying. Don't be tempted. Sounds too good to be true.
There's also the large market of non-US people needing a US-issued card to buy stuff online from websites that only accept US-issued cards.

Every thread on this topic everywhere on the Internet is filled with:
1. People speculating endlessly with the dumbest theories
2. People referring back to other threads that are filled with #1
3. People making random comments that aren't even related to the question
In an attempt to be helpful, I will summarize what I have spent way too much time reading:
1. Some people did this to get Cash Back awards (example: the old Microsoft Live Search Cash Back) which made the cost actually under face value
2. Some people did this to steal the gift card. Order a $50 gift card for $55, receive it and then claim you never received it. If the seller didn't follow the eBay and Paypal procedures to the letter, they are out.
3. Some people did this to cover their tracks. Order a $50 gift card on eBay, use it to buy something that will be used in a crime.
4. Some people did this to convert a stolen credit card (something with a short shelf life) into gift cards (something with a long shelf life)
In any case, seems dangerous to be a gift card seller on eBay.

link ?

A similar question. Why are some empty cards, such as no value Shell gas gift cards being sold? The pictures are all the same, so I can't even imagine it's a collectible/ special edition. What's the catch?