Recently, an auction ended on ebay for a fake W514 Babe Ruth (miscategorized as a W551):
Link. Only a handful of folks bid on it, so it looks like most people realized it was a reprint. However, it looks like it will still cost someone around $200.
Red Flags
1. This is the most obvious give away that the card is a reprint. If you compare the card #2 in the lower right hand corner of the reprint card, for which I've attached the scans, you will see that the 2 is cutoff. Only the top half of the 2 is showing for the card. Check a genuine W514 Ruth in the next post, and you will see that the #2 on the lower right of the card is not cutoff, and you will see the full 2.
2. This seller does not have many of the typical red flags that you see for someone who sells reprints. He has ~7600 feedback, mostly positive. However, when you check out the description for this Ruth card, he states that the authenticity is unknown. That should raise immediate concerns as a buyer whenever you see a seller that states that they cannot guarantee that the card is genuine.
3. Another common area to check is to see what other cards the seller has. Again, here it looks like the seller is selling a bunch of genuine T206 cards (to my eyes). Therefore, you might start thinking that you caught a deal here, and the seller doesn't know what he has. However, if you also scroll through his sold listings, you will see another Babe Ruth card, which is an obvious fake, as there is no known card for that image for Ruth.
4. One final red flag is that when you look at the scans for the reprint, the front and back have different colors. This is not as obvious as when you see an aged card with cracks on the back, which is typical for fakes. However, if you compare with the genuine card in the next post, you will see that for a real card, the back and front for the card stock are typically the same color, both in sepia. Saying that, this is sometimes a false positive in identifying fakes as cards can undergo some color changes, if they are exposed to light, removed from scrapbook, other environmental conditions, etc. However, this should start raising concerns within you as a buyer that this card may be suspect.
One more thing that I'll add is that the image for the fake does not seem as crisp as the genuine card. And for the fake card, the words seem to all be in bold as compare to the real card. Again, may be hard for you to judge here as you may think that it just may be a bad scan/photo of the card which is a bit blurry.