Sold 2 out of 3 gifts cards: 1x Shell gift card and 2x AMC Theater cards. They needed the Shell gift card to be sent in. I sent it Monday (10/2/17) and got a response by Thursday (10/5/17) that they were unable to check the balance of the Shell card and would be sending it back. However, the 2x AMC Theater cards went through without a problem and I received an email with an Amazon gift card code shortly after the first email (also claimed without a problem).
For reference, I only live 25 miles from their mailing address, so I expected a bit of a quicker response, but either way, I was at least able to sell 2/3 cards. My only gripe is that they didn't explain why they had a hard time checking the balance of the Shell card. I had no problem checking it via buyshellgiftcards.com. Oh well.