The scarier the better.
I want to be too scared to turn out the light. I want my corn patch to give me the creeps as I walk past in the evening. I want to nervously eye the overhanging branches of the trees in the drive way. I want the walnut tree to look skeletal, not just naked when it loses it's leaves in the fall. (It's the perfect Halloween tree)
Blood, guts, and gore galore has it's place as well.
Those vampires and werewolves better be looking at your neck in contemplation of the most efficient way to rip it out, not because they are romantically inclined. The monster (human or 'other') who relishes wading in rivers of blood. When the author gets the description of the sounds of heads being torn off or eyeballs popping out just right and it makes me go 'Eeewww! Yuck!' .
And we can't forget the fun romps through cheesy 'B' territory! Where everyone but the reluctant hero (and sometimes even him) is running around like chickens with their heads cut off trying to defeat or avoid the invaders from the mutating goo. With his never ending ammo and MacGyveresque improvisational skills.
Oh yeah. Definitely Horror. : )