These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Lucifer's Hammer
Harsher in Hindsight: at the very end; the heroes successfully defend the last operational nuclear power plant in the world from the cannibal environmentalist fundies(at the cost of their Gadgeteer Genius - he was diabetic, but chose to make mustard gas to kill the cannibals instead of insulin), but it would only take one lucky mortar shot to destroy the plant, and the only way to keep that from happening is to hunt down the fundies and either take all their weapons or kill them all. To save civilization, they have to fight The War on Terror, and be willing to commit genocide if their enemies refuse to surrender.
Unfortunate Implications: To quote Rational Wiki, this is a novel where "a group led by a former U.S. senator who set up a particularly hardline form of government are the good guys, trying to keep at bay the roaming bands of hippies, black nationalists and cannibals." Another page on the same wiki criticises the book as viciously misogynistic, mentioning a gleeful passage about "the death of feminism".
It may be seen as saying that feminism (along with racial equality, literacy and universal human rights) is a luxury afforded by technological society, which quickly dies in a natural environment. Still a Family-Unfriendly Aesop, but a defensible one.