Canned tomato soup. The store brands are half as much as Campbell's. I doubt anyone could tell the difference in a blind taste test. Yet people all go for the national brand.
I once had a blind taste test to see if I could tell the difference between red bananas and yellow ones. The red ones are sweeter. I had no trouble telling. But, alas, I wanted some red bananas but the chain grocery stores ain't got none. People won't buy them. They're afraid of them. Back when I lived at home my dad would not eat red bananas. He wouldn't even try one.
When I lived in Oregon (a major potato growing state) I had some red potatoes. No one would eat them.
Also in Oregon I got a hold of some blue corn meal. I made some cornbread. No one I knew would even taste it. They were all afraid.
I wish I knew how to run a restaurant. I'd make french fries out of blue potatoes. And nobody would eat them.