Posted By:
D. C. MarkelObviously restored corners in a graded holder is not a good thing, but at least this is detectable and PSA has a buy-back policy.
I believe a much bigger problem that appears to be rampant, especially on NM vintage cards, is the minor mechanical working of corners. Basically, if a corner gets a small ding without any paper lose, or a small corner crease, the damage can be "fixed" and card be graded from typically NM to NM-MT. From what I've been told by some extremely trusted people in the hobby is that one major auction house and fair number of eBay dealers make a practice of this routinely. The most bizarre thing to me is that some, but not many, collectors I know have been warned of this and don't seem to be bothered by it.