Not knowing what a particular dish that you’ve never seen before doesn’t make you dumb.
I have no idea what scalloped potatoes is, I’ve never had it. Maybe it means they bake scallops inside a potato? I have no idea. I’ve never had scallops either, I take it they’re a type of sea food, but as I’ve never run into them I assume they’re not for the working class.
Not everybody can live a fancy lifestyle, or live somewhere where scallops and other fancy foods are affordable for normal people.
So, when they hear of a dish with scallop in the name, it’s not “dumb” to think that it may have scallops, a food they’ve never seen, in it.