Certainly the line spoke by Ratcliffe to Madeline, "that no representative government can long be much better or much worse than the society it represents. Purify society ad you purify the government. But try to purify the government artificially and you only aggravate failure," frames the political discussion of the novel well. Obviously it is the case for the discussions of universal suffrage. (41)
But this bottom-up conception of corruption is also present in the narrative arc of the novel. Madeline's fixation with power, and intent to marry based on her own ambition, ultimately leads to her total disillusionment and rejection of the Washington culture.
And I think this same thinking is present in the DC culture today. Whether you're working with these people or reading about them in the news, it's easy to identify those that are in government for all the wrong reasons. Ultimately, their pernicious motives lead down a path to scandal and embarrassment.