Some cards that get the Auth designation may not actually be "altered", but are categorized that way as there's either a question about the actual state of the card, or there' not a separate way to categorize in the grader's system.
One such category that comes to mind is the "factory cut, but too small". A number of early cards have this, including a good number of T207's - the cuts look normal, just the card is undersized.
Posted in another thread, here's what I believe is such an example.
I'd pick this card up in a heartbeat, any day, and 5 times on Sunday.
Mike