Posted By:
ChrisMike,
The first tip off that the cards are fake is that the seller is listing them as reprints. NEVER buy anything from an ebay auction where the item is being listed as a reprint. Its a dead on guarantee that it is, no matter what else the ad may say about their provenance.
As for the appearance of the cards, if you look at some photos of genuine Goudeys and Cracker Jacks compared to the cards you bought, you will notice immediate differences in color, font, the way the colors bleed (esp. with Goudey's) and the overall "texture" of the card.
The best advice I can give (and I am certainly no expert) is to find a reputable dealer -- there are several links on this board to them if you look -- and buy some low grade commons from these sets. That way you will be able to get an idea of how authentic cards from these sets look and feel.