I watched I am Legend with a few friends tonight and one of them asked whether the aliens from Signs or the vampires from Legend were more believable.
Legend's vampires were hard to get behind, but imagine being an alien capable of intergalactic travel and deciding to invade a planet 70% covered with lethal acid. And it rains this acid. And its inhabitants drink, swim in, and are 60% made of this acid. Would your attack strategy be to sharpen your fingernails, run around buck-fucking naked, and scratch your enemies to death?