Appetite for the Unnatural and Clone Legion vs. hexproof creatures
From the Comprehensive Rules:


  702.11b “Hexproof” on a permanent means “This permanent can’t be the target of spells or abilities your opponents control.”


Appetite for the Unnatural targets the enchantment, not the creature itself, so it will resolve and destroy the enchantment (unless the enchantment itself somehow has hexproof too).

Clone Legion targets a player, not creatures, so unless that player has hexproof, it will make a copy of all their creatures, including the ones with hexproof. Any enchantments on those creatures won't be copied.