Sacrilege! Sacrilege, I say!!! Ketchup belongs nowhere near a hot dog! Cure ye wicked fiend, ye Cloven Hoof, ye Prince of Devils. The ketchup industry has duped you into believing this Sauce of Evil should lay together with a wienerwurst.
But it certainly does belong on a meatloaf sammich. How could you have a meatloaf sandwich without ketchup? I mean, it’s inconceivable.
Sandwich spreads? I normally go with mustard, mayo (homemade when I could be bothered) or horseradish. Butter is wonderful on open-faced veggie sandwiches. MMMmmmm!!! Butter a nice crusty piece of bread and garnish with the freshest tomatoes you can find. Sprinkle a bit of salt and pepper. Heaven. Pure heaven.
Or to take a page from my childhood, substitute chopped green onions for tomato. I’m drooling already.
Bacon grease (we called it “smalec,” the Polish rendering of the Yiddish schmaltz, in our house) is wonderful on plain bread with freshly chopped onions and salt. Also, lard is also quite good with onions and salt, but I can understand your disgust if you don’t agree.
Margarine - can’t stand the stuff on anything (except in my Buffalo Wing sauce, where it’s required.) Will eat it, but will never choose to put it on any sandwich of my own device.
Mayo with capers is good for seafood sandwiches (tuna, fried fish and the like.)
Cream cheese is also excellent with fresh cucumbers and tomatoes. The Hungarians have a lovely spread called “korozott” (there’s a bunch of umlauts I’ve failed to include) which consists of fresh curd cheese (something like farmer’s cheese or cottage cheese), paprika, onions, salt, butter and a bit of mustard. It’s not used with meats, just the aforementioned veggies.