Provenance, provenance, provenance
First, I think people who spend $100,000 on a 1957 Topps Sandy Koufax because it's a PSA 10 are dunderheads (in part because grading has a well known margin of error, as evidenced by people resubmitting cards and getting different grades), but i wrote an entire article about provenance (including a bit about high grade cards) and if they don't care to inquire where a card came from before dropping $100,000 that's their choice and perhaps their eventual downfall. Of course not all cards have verifiable provenance, but $100,000 is a big investment to not even ask where the card came from.
http://www.sportscollectorsdaily.com...ce-collection/
For those who don't want to read the entire article, I'll quote:
"When someone is offering a Gem Mint antique baseball card with perfect razor sharp edges, have you ever considered asking where it was acquired? If the seller himself trimmed the card, he won’t be able to provide documentation that it existed in that condition before he owned it. Clearly, there won’t be solid documentation for many cards– cards are discovered in books, bought as part of group lots, a sales receipt may make no mention of grade–but provenance of high grade cards should be something to keep in the back of your mind."
If collectors started demanding to see where high graded cards came from before they laid down any $, a lot of the alteration problems would be solved right there. Card doctors won't be able to show where they got the card-- though there will no doubt suddenly be a rash of Gem Mint 10s "found in my grandmother's cabinet."
Not that I'm anticipating that the hobby will take this advice (I've mentioned provenance many times over the years visa vie cards and alterations, but it always appears to fall on deaf ears). But an individual collector reading this post can take the initiative with his own purchases.
