I think I'm paraphrasing Yahtzee (the Resident Evil 5 trailer episode) when he said that true dread and terror comes out of something that truly disturbs the player and makes him or her uncomfortable. It should push the limits of taste and make the player feel uncomfortable whenever possible. Visceral, makers of Dead Space and Dante's Inferno, really do seem to have no limits when it comes to this. They want to freak you out, and by God they are going to do it.