Where do you draw the line?

For me, it's if an item would be utterly trivial to leave off in the preparation. Otherwise I'll eat it anyway, maybe take it out myself (e.g. gherkin or tomato in a burger) or just order something else.

I have an ex who would always - ALWAYS - ask for cheese to be melted onto the chips any time something came with chips. Always. Everywhere. It used to really wind me up and I'm not quite sure why.