If the sandwich includes tomatoes and cheese, they should be next to one another. Tomatoes and cheese are a marriage made in Heaven and it is a sin to separate them.
Sandwich trivia:
If you have ever made a sandwich with bread product (bread, bagel, sandwich thin, etc) containing poppy seeds, a careful search of the kitchen will find at least a single poppy seed.
/Sandwich trivia
Mayonnaise goes on each piece of bread, and between each layer of whatever gets stacked within. I say “mayonnaise.” Kraft and Hellmann’s products are not mayonnaise. There’s only one.
Typical sandwiches (non-subs) should be served halved. And the cut should always be diagonal.
The only time sweet pickles should go on a sandwich is tuna salad.
The top layer of bread should never be too crusty or it will cut the roof of your mouth.
True story: I once made a sandwich and was too lazy to slice it in half. I figured it would taste the same anyway. As I began to eat it, somebody else walked into the kitchen and I actually felt embarrassment from being seen eating an unsliced sandwich. It felt a bit like getting caught drinking directly from the milk jug.
See, I feel embarrassed when someone sees me eating a sliced sandwich as if I got caught drinking out of a sippy cup.
Hot meatloaf requires gravy. Ketchup is to be reserved for next day, when the leftover meatloaf is cold and can be sandwichized.
Peanut butter and jelly sandwiches should be composed of smooth peanut butter and grape jelly. Crunchy peanut butter puts the focus on the crunch rather than the smooth melding of peanut butter and jelly. Grape is just bland enough to add sweetness without making you think of another fruit like apricots or oranges.
Commercial mayo is pretty bland. Home made mayo is awesome. My home made garlic mayo will put hairs on your chest. 
I put mayo on the bottom slice of bread, mustard on the top. Then the meat. Then the cheese. Then the pickles (DILL, not sweet, drained). Then the tomato (salted). Then the lettuce (which creates the moisture barrier between the tomato and the top slice).
Fried egg sandwiches are just wrong if they don’t also have cheese and bacon on them. The cheese needs to be in between so the bacon and the egg melts it well. And it has to be American cheese. NO MAYO. Although my husband likes jelly on his.
And I never cut my sandwiches in half until I was an adult and hardly ever do so now. I am
told it is an etiquette rule to do so for hamburgers, however.
Ketchup does not belong on any sandwich, ever. Just hamburgers and hotdogs and french fries.
- The first rule of sandwiches is we don’t talk about sandwiches.
Bread and butter pickles go ON the sandwich, in slices.
Dill pickles go NEXT TO the sandwich, in spears.
People, people, enough talk of what goes on fried egg sandwiches. Everybody who’s anybody knows that it’s salsa what belongs on fried egg sandwiches. And cheese. And ham. So shall it be written, so shall it be done. On earth as it is in heaven.
Minority maybe, but you’re not alone. I like to be able to actually taste the main ingredient. And I hate comments about “eating it dry”. If the bread is really dry, slathering weird goop on it won’t help.
Uh-oh.
According to my spouse, mustard is ONLY spread on the meat, never on the bread. I don’t know where she got that crazy idea.
Oh, and another rule: peanut butter and mayonnaise sandwiches are folded, not cut. Otherwise the flavor runs out. My brother taught me that as a wee bairn, so it must be true.
All cold sandwiches must be eaten with chips; hot ones with fries. If there’s no form of potatoey side than I don’t even want the sandwich ( and I do not mean the abomination that is potato salad).
Did anyone else read that as ‘embolism’? Probably what you’ll get if you eat too much mayo.
Fine, I’ll have your sandwiches.