Not a proof: 1880s Allen & Ginter blank backed ‘card’ handcut from a lithograph album page
The trading card hobby puts a premium on proof cards. Proofs are pre-production test cards the printers use to check graphics and text before the final print run. Vintage card proofs are often blank backed, sometimes on different stock than the final cards, often with hand cut borders and little pencil written crosses on the borders. Proofs can sell for good money as they are rare and offer a look at the creation of the cards.
The collector should be aware that many cards resembling that proofs aren’t proofs. The manufacturers sometimes accidentally printed cards with blank backs and inserted them into the packs of gum or tobacco. These aren’t proofs, but printing errors.
There are also ‘cards’ that were long ago scissors cut from vintage advertising posters, tobacco albums and kids’ notebooks. As these cutouts have hand cut borders, blank backs and different than normal stocks, they are often mistakenly called proofs.
Collectors will also come across printer’s scraps, often of T206 baseball cards. These scraps came from a printer’s rejected sheet, often with poorly printed images, bad color registration and other graphics problems– which is why it was rejected, or scrapped, by the printer. These rejected sheets were rescued from the trash bin by workers, often to be taken home for the kids. The individual scrap cards that we see today were hand cut from the sheets. As the cards are hand cut, often oversized and usually with printing defects, they are often mistaken for proofs. As with the above mentioned blank backed cards, scraps are simply factory mistakes.
Not a proof: misprinted, funky cut 1909-11 T206 baseball card. Commonly referred to as a ‘scrap.’
As you can see there are lots of non-proof cards that resemble proofs. When in doubt it’s best to bid on an unusual card assuming it isn’t a proof, because it likely isn’t. Scraps and other printing mistakes are collectable, but are much more plentiful and inexpensive than genuine proofs.
Looking at Artifacts and Ideas 
I have five printing proofs of an odd issue of cards published by Joe Lowe NYC in 1959. they are for the Aurora/Sicle “famous fighters” series of trading cards. I have done extensive research on these cards as I found a hoard of uncirculated cards in an Estate the deceased owner drove deliveries for Aurora and was given this hoard from one of the founders of Aurora Abe Shikes who was the marketing guru behind the Company. Others call this set Sicle Red Ball “airplanes” but in reality as I have information on what Abe called the cards it is Aurora “famous fighters” the set was published in two separate types. The Aurora set first in early 1959 which had 21 cards with both Aurora and Sicle advertising on the back then again in 1959 and 1960 in a series of 72 cards without Aurora advertising as the later set had planes that did not represent Aurora box tops of famous fighters. In any case I have five of the cards that are oversized with larger margins one marked with a P within a circle on the back they have less sizing on the cards so different paper than the normal run. Almost no gloss..I was a printer when I finished college so I do know what a proof is and I am certain these were given to Abe to approve the run. Does this give them more value. These are in excellent condition but have been handled as other cards are NM/M ..Any help would be appreciated,
If you say they’re proofs, I don’t doubt you. Proofs for old trading card sets are desirable, and you could try consigning them to one of the big auction houses such as Legendary Auctions, Robert Edward Auctions, Heritage Auctions or Lelands. They all specialize in old trading cards and have before sold proofs and original art for vintage card sets. Thanks