It varies by episode. Krabs has done some terrible things. So has Plankton. Mr. Krabs physically abused a pet, sold Spongebob's soul for 62 cents, and drove his old friend to become so afraid that he sat in the middle of the road waiting to die. Plankton took someone's brain out to put into a robotic slave, is often uncaring toward his wife, and posed as a woman to emotionally manipulate and crush his old best friend's emotions. Just a few examples. Both of them have done some pretty terrible things. But they've also both done good things. I think it really does vary.