I was at a card show a couple years back and one of the vendors (who has not done anymore shows in the Jackson-area) sold a Michael Jordon Rookie Card... that ended up being fake. The buyer took it to one of the other vendors who was buying MJ Rookie Cards. The vendor explained to him that it was fake and took him to a website that showed a real and fake MJ Rookie Card side-by-side.
The buyer returned to the vendor that sold him the card and asked for his money back... was told NO!... then demanded his money back... again he was told NO!... then he had the police get involved... and the vendor reluctantly gave the buyer his money back... screamed at just about everyone in the building... and was stupid enough to talk about one of the police officer's mother, before being escorted from the building in handcuffs.
So... long story short... I have NEVER purchased a FAKE card, but have seen what happens when you sell one!