When Is A 3c Silver A 3c Nickel? 1866

To add to my CAC confusion, their "coins accepted" calls out specific Lincoln Cent doubled dies and specific Jefferson 5c DDO, RPD and OMM as coins they accept, but not 1936 Type 3 or 1972 Type 2 DDOs. If all they're doing is slapping an A or B quality sticker on the grade, why call out that handful of varieties as accepted? It implies they're also validating more than just the grade, but I don't see this explained anywhere. Perhaps they're confused about what they do too. Oh well, this is merely an intellectual exercise for me, I'll don't really care what CAC thinks about the coins I have or buy.

Thanks for clarifying, @jimbucks. If you want to sell it but GC won't take it with the slab error, I can appreciate your quandary.