[drc]

Most cards graded by PSA and SGC as Authentic are altered. That's why they got that designation.

I've seen many good looking Auth cards sell for well above their grade value.

There are instances where unaltered cards get the AUTH grade, such as autographed cards, where the seller asked only for the AUTH grade and rare/oddball/esoteric/unusual cards where the graders don't have enough experience/knowledge of the issue to grade.