How would conduct founded on "hard rock" differ from conduct founded on "wet marshes"? Discuss what you think the passage implies about the narrator's state of mind?

The narrator is merely stating his opinion of the conduct of others, noting that no matter how hard one tries to remain unbiased, there are certain things that are unacceptable. In the above quote, he uses the example of "hard rock" or "wet marshes", which we can infer to mean conduct performed in normal circumstances..... to conduct performed out of a sense of desperation.