[dkersten]

I'm not an outsider, yet I always answer "no thanks".

I use butter and mayo for one of two things: flavour (eg I love kerry gold on toast ;-) often nothing else) or moisture - but if I don't need the moisture, usually because I've got tomato, peppers, coleslaw, relish or something else providing that, I will leave butter and mayo out. Unless I want them for the flavour. (As an side, I don't understand why people would ever want butter on a breakfast roll)

[stan_rogers]

"... usually because I've got tomato, peppers, coleslaw, relish or something else providing that..."

These are precisely the instances in which I would want something oily (butter, marg or mayo) as waterproofing for the bread. (Mustard also works, if it's appropriate for the sandwich.) "Everyone has the gout," as they (don't actually) say in French.

[CalRobert]

I feel I should give credit where it's due - while I'm no fan of butter on sandwiches, the butter here is fantastic, and makes for delicious toast, popcorn, etc.

I just don't need a peanut butter and butter and jelly sandwich.