I've had experience with a variety of cards.

With Citi, the "unbilled activity" usually shows up as almost exactly (or slightly below) the interbank rate for the day of the purchase. Then a separate 3% of all foreign purchases shows up in finance charges on my statement.

With Target Visa, the "unbilled activity" usually shows up as almost exactly interbank rate +1%. There is no separate line item.

With CapitalOne, the "unbilled activity" usually shows up as almost exactly (or slightly below) the interbank rate for the day of the purchase. There is no separate line item.

Bottom line: CapitalOne eats the Visa/MC fee. Others don't.