You can purchase gift cards at supermarkets for Amazon.com, Starbucks and many other chains, giving you an effective 6% cash back at those stores.
I just talked to American Express online chat and the rep I talked to said this is not and has not ever been the case. I said,
"So if I go into the grocery store and buy $30 in groceries and then get a $20 starbucks card, I don't get the 6% on the starbucks?"
and the rep said no that portion would not be included.
Could someone tell me if this rep is correct, I find it a little concerning that there are many reputable websites and publications that all say otherwise.