Spandam is evil, but he's a product of the World Government. Some middle management asshole who kissed enough ass to be put in a position of power that he's vastly underqualified for.
Arlong is evil, but he thinks he's the hero.
Crocodile is pretty damn evil. I know he had his redemption moments from Marineford, but the dude is a sociopath in Alabasta.
Kaido is evil, but because he's given up on everything. He basically just said "fuck it" and wants to hit the restart button on the world.
Akainu thinks he's a superhero, when in reality he's just an over glorified body guard for the worlds ruling class
But Doflamingo is the last one of these people I would want to meet.