I have already seen some sites that have changed from instant to one confirmation because of people trying to scam
People attacking sites that requires 0 deposit will get nothing from that double spend attacks as they are not able to withdraw it. Its just a free play for them
People can abused this. If they win then they will push through the transaction by sending in an input but if they dont than they wont send in an input. Repeat this process if you lose by making new account, Keep on repeating this and it will make things easier since you dont need to wait for it
That makes no sense. At all. Really. Let's say I deposit 0.025 btc and do the double spend trick. I have the coins in the account and I make 0.05 btc. How am I pushing it through? Funding it with 0.025 btc? So basically I'm depositing like I should have in the first place? You get what I mean? How are they pushing it through?
The way it is done is they deposit with 0 fee and make the bet with full amount, if they win they wait for it to get confirmed so they can take the winnings out, but if they don't they make another transaction with higher fee to another address which is owned by them and this is how they abuse the no confirmation deposits. It is not easy to do but there have been instances where it was done and which is why most casinos have opted for 1 confirmation deposits required to play.
Read more about it here: https://bitcointalksearch.org/topic/m.10987995