Wire transfers are very secure. Can't think of an instance in which one of them have been reversed.
Here in the United States a Wire Transfer (or any other bank related exchange of cash) can be reversed by a court order (assuming the money ended up in a US account), however since it requires a court order it would probably be extremely hard for a Bitcoin exchange scammer to scam you of your money.
I'm not sure about it, but I'd guess that courts of other nations can probably do similar things.