This is another thing that bugs me. Apparently it bugs one of my work buddies, Erin.
It's when people use "quotation marks" when they're not really "necessary." Or in this case, misleading. It's not soup, it's "soup."
I understand they're usually just trying to add "emphasis" to their statement or signs. But there are countless other ways (correct ones, I might add) that will do the job better.
For more "unnecessary" quotations, go to the Unnecessary Quotes website. Be prepared to be disappointed.