Since I've been asked if this thread is referring to a particular card, I'll spill the beans.
My question was more of a general appraisal of the situation, not perfectly specific. The actual card in question was a 1968 #280 Mickey Mantle graded a PSA 7 ST.
Here is a list of a bunch of straight PSA 7 sales from the past couple of months:
DATEPRICE
6/25/2018$295.007362355049949eBayprobstein123Auction290 10693
6/24/2018$336.997263757761262eBayemoncardsAuction902231 98
6/14/2018$415.007142821778318eBaypwcc_auctionsAuction23 960047
6/8/2018$370.007282993806728eBaytc.8787Buy It Now25619735
6/7/2018$325.007253649975328eBayazsportsrelicsBest Offer21002103
6/5/2018$330.007332664729906eBaychgocubs74Auction19978 737
6/4/2018$377.657123152349659eBaydiamondcardboardBuy It Now29010693
5/27/2018$315.007312139110876eBayog60jb32Auction0717414 0
5/21/2018$432.527153022007174eBaysavannahgatorAuction05 042097
5/16/2018$294.007209Mile High Card CompanyExtra Innings May 2018Auction29010693
5/15/2018$330.007132612041941eBaygregmorriscardsAuction 28636439
5/15/2018$300.007292565095758eBaytexasholdemtomBuy It Now01517820
5/13/2018$350.007372287903567eBaycaughtlooking2000Buy It Now19978737
5/13/2018$300.797142775541615eBay808resellBest Offer27636349
5/7/2018$397.777192499380537eBayprestonwms34Buy It Now27045150
5/6/2018$350.007332635796118eBaypean32Auction15345337
5/4/2018$425.007192507525159eBayscotts_vintage_cardsBu y It Now28183467
4/24/2018$299.997302714157002eBaydaisywoodyemmaBuy It Now22165975
4/16/2018$411.997352323923652eBaypwcc_auctionsAuction28 710441
These average out at $350 (with a low of $294 and a high of $432.52) and the lowest straight 7 BIN available on ebay is for $379.99.
After exchanging some messages with the seller (and studying the scans), I feel quite confident that the stains are the sort of thing that could be/should have been easily removed with a pair of your wife's (or your own??) pantyhose.
The card is in an older slab and the centering isn't ideal, but I was able to pick it up for a cool $200, which made it quite worthwhile to me. Unless it turns out I really screwed the pooch, I'll post better/clearer scans when it arrives.
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