Another suspicious example:
1968 Topps Phil Roof: a very abundant common card. In fact 3 PSA 9s all sold in the past couple months: average sale price $16. This card in PSA 9 is so abundant, sellers can't get rid of them. I should know, I've got some. At this moment, there are 12 (!) different PSA 9 copies of this card available BIN selling for under $40, just not moving at all:
$17
$23
$24
$24
$24
$25
$27
$27.5
$28
$30
$30
$36
But here comes an auction (
https://www.ebay.com/itm/1968-Topps-...T/384048185877), and the card is now feverishly bid up to $52. Anyone who closely follows '68 cards knows this makes absolutely 0 sense. No bubble talk could even explain it.