My DH and in-laws do this too. I am the only one in the house who eats real butter, and who doesn't put spread on every sandwich. What gets me most is the bacon sandwiches, with bacon cooked in oil, thick spread on both pieces of bread, and brown sauce. I can't even think about it without shuddering. But then, I love peanut butter, and they all think it's disgusting, so I think it just comes down to what you grew up with.