Even if it doesn't work, or isn't profitable, maybe it's effective as a denial of service attack against the site, polluting their wallet with transactions which will never confirm.
Good and interesting point, time for me to go read up on double spend attacks some more and the results of one on a victims wallet.
Well, SD pays out unconfirmed bets. When your bet loses, you get 0.5% of it back, and the other 99.5% goes into their wallet as change, and is used to pay out the winning bets. If the wallet has lots of old confirmed change from losing bets, that's fine, but what if the only coins available in the wallet are unconfirmed change from losing bets?
When you win, and they pay you out with unconfirmed change from other people's losing bets, it's possible that at least one of those losing bets was double-spent and never confirms. That means the 0.5% returned payment never confirms, and so neither does the change you were paid with. That in turns means your winning payment won't confirm.
I don't know how you fix that, but I'm guessing it requires manual intervention.
