I’m pretty sure this is the first great work of literature that uses the word ‘shit-heel’ in it.
So far everyone who runs a business is a thief or a son-of-a-bitch. Steinbeck seems to be saying that nobody who runs a business is any good. And while I get his point of speaking for those who can’t speak for themselves, the taken-advantage-of, it’s a more nuanced argument than just black and white.