Also, just to add to this topic a bit.
I think body language, style, and runup of the bowler contribute to the 'scareiness' factor as well. There is no doubt that Wood is freakishly scary when he bowls, but generally he has a jovial, happy-go-lucky personality, which I think makes him seem less scary than he is. (don't get me wrong, i'm not saying that he shouldn't be 'the class clown' haha, but it just makes him a seem a little less intimidating.)
Mitchell Johnson's appearance just looks intimidating. With his tattoos, stacked biceps, height, and facial hair. And when he is steaming in, giving it his all, his looks amplify his scare factor.
I know Murali is a spinner. But there was something about his eyes that was intimidating. He looked like a man possessed, whose mission it was to take your wicket. A bit like Medusa with the cricket ball.
Lastly, Shoaib and his run-up! The guy would run in from the 30 yard circle at lightning speed. Perhaps that extra time would make batsmen overthink. Also, the crowd would progessivly chant "ohhhhh" louder and louder as he ran up, which, as a batsman, would probably create more butterflies.
In conclusion, Rauf should get tattoos, Naseem should bowl cross-eyed, and Shaheen should bulk up
