Buddha said even acting with good intentions can lead to a bad result, and so advocated no-deed. The take-away here is that if you must act, be aware that you are taking a gamble.
There are dark deeds with dark results.
There are bright deeds with bright results.
There are dark and bright deeds with dark and bright results.
There are neither dark nor bright ...
One way to arrive at an ethical stance is by assessing how it relates to your goals.
If your goals are utilitarian for example (ie: you generally aspire to maximise pleasure or wellbeing and minimise pain or suffering for all affected individuals), then deriving pleasure at another person's expense will likely only be ethical if you deem that the pain you ...