Suppose you pay me a thousand dollars to do something evil, and I lie to a friend to earn that thousand dollars. Why did I lie? Because it was evil. Why was I doing something evil? Because it would earn me a thousand dollars. This shows that it is possible to do something evil because it is evil. However, note also that this example does not challenge the doctrine that one always acts under the guise of the good. For one lies because it is evil, yes. But, if we give more detail, we need to say: because the evil of the lie is instrumentally good. So, interestingly, the doctrine that one acts under the guise of the good is quite compatible with intending something under the description "is an evil", and choosing it because it is an evil, as long as that is not a description of the ultimate end.