I don't like spaghetti with only ketchup, but I will add ketchup to marinara. I've also added paprika or soy sauce. Probably a lot of things would work, as long as it would be in combo with spaghetti sauce (marinara being my favorite).
"For me, it is far better to grasp the Universe as it really is than to persist in delusion, however satisfying and reassuring." - Carl Sagan