Blew $250 on a slab of X-Men #1 and it came back a 6.5, lesson learned
Bought a raw copy at a show in Denver back in March thinking it was an easy 8.0, but CGC smacked it with a 6.5 and now I'm out the grading fee plus shipping on a book I overpaid for. What's the dumbest raw gamble you've taken at a con that didn't grade out?