Huh, been there, done that.
I’ll throw in my monkey, too, here’s the story:
A few years ago I’ve bought an expensive piece of jewelry ($5K) intended as a gift and, naturally, I charged it to mine DL Amex.
It turned out that I would never use this gift, but when I came to return the item four months later, my DL was long gone – canceled after 1 free year. I did not even remember which card I used, so when clerk tried to auto-refund it – transaction got rejected. For the moment we stayed stunned – clerk did not know how to react, and I realized that I hit THE loophole. The clerk was still mumbling something about not being able to refund cash, when I was handling him my Business Amex (no miles, no MR) and telling him that my account # been changed. Boy, did it make him happy. Later I transferred in my -$5K balance (free for Bus Amex).

I guess I did step on the Dark Side when I repeated this tran last summer – but my 9-month old DL Amex was offering double miles, and I could not resist.

So, like our messenger running back to Athens, I do believe there’s something between black and white. Will I do it again ?...