Since it's difficult to determine whether a human produced a particular piece of content, a good alternative would be to determine whether there's any incentive

Since it's difficult to determine whether a human produced a particular piece of content, a good alternative would be to determine whether there's any incentive for a bot to produce such content, and target that instead. Ads, analytics, affiliate links, etc. Sure, you could still make a bot that auto-generates blogspam without the aforementioned things and rank as high as before, but what's the point if you removed the very things that get you paid? There's plenty of things out there that are trivially spammable but outside of isolated cases (where the objective is to cause damage/annoyance rather than profit) nobody is spamming them because there's no profit to be made by doing so.