I remember having a similar reaction to myself while seeing the movie The Road to Perdition. This movie had a huge amount of bloody violence, but what had me almost hiding under my seat in horror was a scene in which Tom Hanks was teaching his son to drive a standard transmission car.
I guess at a certain point, the horrific stuff doesn’t seem real. But everyone has heard a new driver grind the gears, and you can imagine (if not pleasantly) someone’s eating cheddar with their apple pie.
Anyone ever heard the song Ed Gein?
Eddie Gein, is on the scene
With his sausage makin’ machine
Well he’s lost his head but he’s got a heart
(And various other body parts)
A-waaa-ooooo chop, chop
A-waaa-ooooo chop, chop
I’d just like to say that my favorite part of the Ed Gein movie is Heather Gettings as a Nazi.
I like the way you think. 
Now I’m gonna crave those two things all the rest of today. [sub]Darn you.[/sub]
And everyone else who doesn’t like apple pie with cheddar cheese: Y’all are weird and have no idea what you’re missing!
PS: Mmmm… liver.
After making light of the pie/cheese thing, I would like to get back to the original point of the OP… What is it about our society that we feel violence and serial killings to be interesting, but strange food consmption produces such a reaction? I guess it depends on the cultural period. In the past, violence as depicted on stage (think Greek through Elizabethan plays) was acceptable, but women on stage were banned because that would make the audience too uncomfortable. Back to the food, Steven Speilberg used this reaction in *Indiana Jones and the Temple of Doom. * Most people I talked to were more disturbed by the scene where Indy and his crew were served a feast of monkey brains and steamed beetles than they were by the scene of a man’s heart being ripped from his chest.
Actually, it’s not too difficult to understand. Not very many of us have seen someone reduced to steaming piles of entrails with a few applications of a sharp gutting knife. We have however all eaten many different types of food and are used to certain combinations, hence the “ook” reaction to weird food combinations.
Eww eww eww! Wrong is wrong. Serial killing is one thing - but certain acts are just absolutely immoral. There is no justification for putting cheddar cheese on your apple pie.
Now why isn’t there a barfing smiley?