Unfortunately, it is impossible to do this -- even strict objective and unbiased rules will piss people off.
The classic example I can think of, that has already generated headlines, concerns nudity policies in social media (Facebook in particular) that have flagged breastfeeding mothers for "nudity" (and thus ticked people off). A "by the letter" policy risks much more of this sort of thing... flagging something as "bad" that much of the social norm says isn't really a big deal.
One other thing I would worry about with "objective" rules is what culture determines the "watch list". The cultural norms for what is taboo actually does vary to some degree from culture to culture. Youtube is used heavily in so many countries, with diverse cultures. How can a single policy encompass the social norms of countries as diverse as, say, heavy Youtube using countries such as India, Japan, the UK, Germany, and the US? (And this isn't even accounting for the diversity of culture within these countries.)
As an example, the swastika, which is extremely taboo in Germany and triggers "hate speech" flags in much of the rest of the West, is (usually styled differently but still) a religious symbol in India. You could create a generic flag category for "swastika", but chances are this will eventually flag some, say, Hindu content from India and tick those people off.
I suppose you could structure the rules to account for as many cultural norms as possible, but that can get very complicated fast.