Humans tend to be messy.
Not necessarily in terms of picking up after themselves, although plenty are like that, but rather in terms of not being able to be categorised cleanly.
You think you can declare that yes, this person here is evil and amoral, and then you find out that they support a local orphanage. Or you find that this scientist who cured a horrible disease also beats their partner, so, they still good?
The vast majority of people are not purely evil, or purely good, just various shades of messy.
Thus beware of those who sell cleaning supplies…