Listing items with the intention of praying on people's mistakes is perhaps not a scam, but it is unethical. If this was the real world, I am quite certain you could end up prosecuted for it and eventually declared guilty to some type of economic crime.
Assuming we grant that such an action would be illegal AND immoral in the real world, is even this much enough to conclude that such an action is immoral in Entropia? On the view that Entropia is not a game, but a virtual extension to the real world, it is plausible that such an argument could be made, but I think it's quite clear that Entropia, if perhaps ambiguous eight years ago, HAS evolved into what most people would consider a game. On the view that Entropia is a game, it doesn't seem at all obvious that virtual actions within the game, which mimic certain real-world actions, inherit the moral dimension of these real-world actions automatically, just by virtue of mimicking them. In fact, it seems clear that they do not; consider the question of whether it is morally wrong to kill someone in the ring at Twin for the sake of enjoyment, versus the question of whether it is morally wrong to kill someone in real life for the sake of enjoyment. I think there's clearly a difference based on the fact that the first act is virtual, within the context of a game.
Does the fact that the avatar will revive in game explain away the moral difference? I don't think it does. Some video games have a "Hardcore" mode, where killed avatars are lost forever, yet killing such an avatar in an environment that encourages PVP is still not morally equivalent to real-world murder.
Does the fact that real money is tied to Entropia explain it away? Clearly not, since any competitive game could be played for money. If we were to wager $100 on a game of chess, would the fact that real money is tied to the outcome make it immoral to take advantage of my game play mistakes? Would it make virtual actions which mimic immoral real-world actions (killing the queen) immoral?
This is not to say that nothing in Entropia is morally wrong; I agree that some things are. However, to demonstrate that an action in Entropia is wrong, one needs to make an argument that leads to that precise conclusion, not the conclusion that the action it mimics would be wrong in real life.