see, I hate mayonnaise, but there are two applications where it's perfectly fine (the very thin layer on a toasted sandwich, and a little bit to make tuna salad). do you find there's any single application where ketchup is fine?
Not who you are asking but I hate ketchup as a condiment with a burning passion, but can use it as an ingredient, so cocktail sauce or really anything where it is sort of hidden, it's fine. It's just way too sweet on its own to use the way people use it.
I like mayo and hot sauce, mixed, on fries. Tartar sauce, anything you like on other potatoes is good (gravy, cheese, salsa, chili powder, sour cream)