We are more likely to think that harmful things are intentional

When side effects of the action is a negative outcome, people are more willing to say that the agent caused the harm. This is not the case when the outcome is positive or helpful. Recent studies with children show that such effects are present as early as at three years of age, suggesting that we are endowed with a capacity that is more likely to perceive actions as intentional when they are morally bad than when they are morally good.

-Thus wrote Marc D. Hauser in Moral Minds pp. 51-52
Referencing:
Knobe J. : Intentional action in folk psychology: an experimental investigation
Knobe, J. :Intentional Action and Side Effects in Ordinary Language
Leslie, A. M., Knobe, J.& Cohen, A . Acting Intentionally and the Side-Effect Effect