I've recently begun shopping around for a copy of the '78 Topps Trammell/Molitor rookie card, and I've noticed what seems to be a really common issue of the bottom of the card around the red outline above "rookie shortstops" being pretty noticeably unclean. I've pulled a few pictures from eBay listings as examples below. Each of the 3 images I used were PSA graded copies, and had gotten grades up to a 7, so it doesn't seem like it's something that severely limits the grade potential
Some examples of this almost look like residue from the gum that was in these packs? But I'm kind of thinking this is more an ink bleed or wet ink dripping issue from printing imperfections. I'm curious if anyone knows the source of this, because it looks to be very common with this card