In "The Devil and Tom Walker", what does the Devil think of the whites? Why?
The Devil ("Old Scratch") seems to have a somewhat dismissive and lowly opinion of white men, although this is mostly drawn from inference, as he has very little specifically to say. The only direct statement that we might draw this conclusion from is that he refers to whites as "savages".
In the context of the story, calling whites savages is meant as an ironic insult. Scratch is referring to how the whites drove out and annihilated the "red men" (Native Americans) and calls them savages for it, when in fact it was commonly the natives who were referred to as savages, at least in part because they weren't Christians. This furthers the irony of the statement; to the Devil, things are reversed, and Christians are the savages because they killed his loyal servants. However, in the meta-context, this seems to suggest that Irving's opinion of the natives was that they were, in fact, savages, although this might read too far into it.
It appears as though Scratch considers the whites to be boring by comparison to their red predecessors; he laments that while the natives made human sacrifices to him, he must now "amuse himself" by undermining the dominant white society.