Hacked Items

There exists the same issue in Diablo II where a high fraction of all items and currency are illegit dupes. People stopped caring, other than the fact that the items could disappear on you, merely because their money goes towards getting an item they need in which they're paying the correct price for. You can't tell it's counterfeit, you're paying retail price, only difference is who's gaining the profit. Of course it's illegit though.

In D2 you can buy unidentified items such as Windforce. To the best of my knowledge an unid item cannot be a dupe.

However, Maple is a lot more money-oriented, so the hackers can sell their 50 int saunas for $$$. I know a guy who seriously considered spending 7,000 dollars to buy all-perfect gear for his character. Two guesses where those perfect items would come from.