Should the noun 'dressing' be plural after a list of adjectives?

Question

When offering multiple salad dressing choices, should it be "ranch and Italian dressing" or "ranch and Italian dressings"?

Answer 1

Things that are separate can be plural: They served (both) ranch and Italian dressings.
Things that are together can be singular: It's made with (both) ranch and Italian dressing.

Many situations can be described either way, depending on what the speaker intends.
And depending, just as often, on how the listener manages to decode the speaker's intention.
Neither of which is likely to be completely exact.

When discussing liquid objects, the possibility of blending is always possible. Liquid blends often get different descriptions, and in general liquids are not count nouns. But this is really about types of salad dressing, not the dressings themselves.

Count-noun usages of mass nouns frequently refer to number of types: seven seas, fifteen inks, etc.
So you have your choice in the case of salad dressings.

Answer 2

The only complication here is the allurement of a non-count usage of 'dressing'.

You'd surely say 'French and Italian footballers'. And I'd certainly use 'robusta and arabica coffees'.

'French and Italian wine/s' would depend on context, and might be a difficult choice in some contexts. As would 'Swiss and French cheese/s'. However, I can't think of any context where I'd choose 'ranch and Italian dressing'.