Let this be a brief resource for those finding themselves asking "is there anything I should save" before throwing away bulk late 80's and early 90's cards.
I am NOT covering promos, inserts, test issues, tiffany sets because those are all very well covered on this board and others like the collector's universe and net54 sites.
This is stuff that can be found in anyone's junk era stash. A list of pack-issued rarities to pull aside before trashing or giving away your junk era stuff. This DOES NOT mean you will make a ton of cash in their sales as the E&V market is rather volatile. These are items that compared to the outrageous production numbers of this era, are genuinely scarcer.
1987 Topps Dave Lopes #4 with 1985 copyright on back (also, plate errors can make the copyright appear as 1957)
1987 Topps Greg Matthews with red neck, not flesh colored.
1987 Topps Turn Back The Clock with yellow dates on front
1988 Donruss Ray Knight with white or dark colored scar on neck
1988 Donruss Nelson Liriano with natural colored face, blacked-out version is the common version.
1988 Score Highlights cards with missing text. Several cards in this subset have been found with one or two words deleted or "whited-out" on back.
1988 Topps Glossy Offer Insert with black arrow over text on front
1988 Topps Glossy Offer Insert with silver arrow over text on front
1988 Topps Glossy Offer Insert without arrow and "cards not included" text on front
1988 Topps Angles TL with magenta stripe over Joyner's arm
1988 Topps John Tudor missing most of name on back
1988 Topps Tom Candiotti missing name on front
1988 Topps Keith Comstock with yellow name on front
1989 Fleer Checklists with positions
1989 Fleer Randy Johnson Marlboro sign and their numerous correction attempts (plenty of info out there on these)
1989 Score cards missing copyrights. These may fall into promo category as I have heard conflicting stories about their origins, included them being pack issued.
1989 Topps Tony Oliva missing copyright on back
1989 Topps Tony Oliva with blacked-out copyright on back (one of the rarest Topps variations produced)
1989 Topps Ed Hearn with blue streak over cheek.
1989 Topps Ryne Sandberg All-Star with large pink blotch over helmet
1989 Topps Company Store and Glossy Offer Insert cards printed on vanilla bean stock
1990 Donruss Grand Slammers Todd Benzinger with red star on front
1990 Donruss Bo Jackson DK with "redone i in Diamond Kings" whatever that means, it's been catalogued since 1990.
1990 Donruss All-Stars without yellow star on front (only a few known examples)
1990 Donruss All-Stars with black lines through star on front (Harold Baines is not particularly rare, other subjects are very rare)
1990 Fleer Dave Martinez yellow '90 on front
1990 Fleer Tracy Jones and Jose Lind with pink name banners on front (other players exist)
1990 Score Jim Abbott, Felix Jose and other red bordered subjects with red wedges by their names on front
1990 Score Milt Cuyler with ghost 9 in 998 visible. Whiteout/airbrushing visible over errant 9 in stats on back.
1990 Score Rickey Henderson and Will Clark MVP's with TM printed outside of box by AL/NL logo
1990 Upper Deck Ben McDonald with blank white circle on front
1990 Upper Deck Mike Witt with black box on back
1990 Upper Deck Checklist #800 with black box on back (if exists)
1991 Fleer Brewers Checklist with same checklist on both sides
1991 Leaf Gold Rookies with regular numbering on back
1991 Score Scott Chiamparino pitches Left
1991 Score Nolan Ryan HL with white stat box on back
1991 Topps Oil Can Boyd with black border around flag tip in 40th logo on front
1991 Topps A*B* print codes (except Daryl Boston...fairly common)
1991 Topps Mark Whiten hand outside border
1991 Topps Doug Drabek white border
1991 Topps Chris Hoiles white border
1991 Topps Joe Morgan 87 hits for Boggs on back
1991 Topps Randy Bush without print code
1991 Topps Sweepstakes Inserts with X and mailing address (extremely rare)
1991 Upper Deck Hologram variations...NHL, 1990, Comic Ball and 1992 type holograms on back
1991 Upper Deck Luis Salazar with print defect over i in name on back
1991 Upper Deck Milt Thompson with print defect over 86 in stats on back
1991 Upper Deck Don Mattingly missing stats on back
1992 Leaf series 2 cards missing stats
1992 Stadium Club with silver foil
1992 Topps Rickey Henderson RB with 1.991 on front
1992 Topps Chipper Jones PROSPECTS card missing black ink on back (unknown origin, some say pack-issued)
1992 Topps Match The Stats SPs...Mickey Mantle, Don Mattingly, Nolan Ryan, Ron Guidry (will update with full list)
1992-1993 Pacific Nolan Ryan Ghost Writing "Say No To Drugs" glow-in-the-dark ink messages on back
1993 Leaf with silver foil (also affects inserts)
1993 Pacific Rob Maurer with Donald Harris (or is it Jose Oliva) photo
1993 Topps Black Gold ABCD
1993 Topps Black Gold Redemptions with and without copyrights on back
1993 Topps Black Gold AB and CD swamped images
1993 Topps Black Gold with flat gold foiling, non-holographic
1993 Upper Deck with white names on front
1993 Upper Deck with 1992 holograms on back (Griffey and Mays Heroes promos exist and are much more common)
1994 Collector's Choice Up Close subset with white or brown bar at bottom on front
1994 Collector's Choice Future Foundation subset white silver signatures and white lettering on front
1994 Topps cards with A or B print codes visible on back (extremely rare, typically A and B sheet players have no print code)
1994 Topps Black Gold ABCD
1994 Upper Deck base cards with silver stat headings on back
1994 Upper Deck electric diamond with silver stat headings on back
1994 Upper Deck Fantasy Team subset with electric diamond printed in bronze foil (very rare)
That's a start. Will update as more comes to mind.