It's down to cultural influences. Westerners regard dogs and cats as domestic pets, but plenty of Eastern countries regard them as simply another food source. Appearence may have an effect - I ate a squid omlette in France years ago, and enjoyed it without knowing the contents until afterwards - had I known, it is doubtful I would have touched it! I do wonder about the appeal of oysters, I know about their supposed effects, but come on, they look and smell awful, they can't taste any better ... can they?