Selected answers from the Dumb SEO Questions G+ community.
Philip Crothers: That title seems a tad misleading. What counts as spammy? It seems most of the duplicate content people would worry about would be considered spammy anyway.
Aleta Curry: That would be my take as well, ; I think it would help if he defines what 'non spammy duplicate content' is in the Google universe. He mentions TOS, which seems clear enough, but what about other times when you duplicate your content?