Up until my 30s when I joined my husband's family, deviled eggs were served as a slightly spicy to very spicy egg. One of the main ingredients was powdered mustard which added greatly to the spiciness. Dad would also add a dash of Tabasco and my recipe includes a touch of cayenne pepper. My eggs are not jalapeno ot but they do have a little bite to them.
The in-laws, on the other hand, use yellow mustard which is much milder and they add sugar to the mixture. I also did not notice any vinegar so I am guessing it is pretty much egg yolk, mayonnaise, mustard and sugar. (my in-laws do not do spice at all)
I argue that these are not deviled eggs because the name "deviled eggs" comes from the fact that the eggs are hot like Hades.
So, deviled eggs.. spicy or sweet?