I don't veto any deal, but that doesn't stop me and the other 11 people in my league from pointing out when one owner is ripping off another (which is generally one owner in particular who is obsessive about baseball to an insane degree and, more to the point, has tons of free time, so he's won 3 of our 4 titles). But no trade should ever be vetoed unless you can prove some sort of disallowed activity.