People make mistakes due to various reasons; lack of knowledge, over-confidence, lack of talent, environmental influence. Seldom the incident is voluntary. You might be on the bitter end of a mishap. We all are, quite frequently. But If it can be explained by stupidity, don't attribute it to malice.
Incompetence is more common than evil, this is not an arbitrary baseless statement. For a species to succeed (humans have, judging by the 7B+ living members), cooperation and reciprocity have to be ingrained in their nature.
It does not mean the intent should be enough to change your decision on something. Most quacks think their medicines really work. Noble intention, but an amulet will not cure your ailment.
Assuming good intent helps us avoid paranoia. If you adopt this mindset, the world will look a little more beautiful and you will be kinder as a person :)