Has this become a thing? I don't see what's so bad about having worked in a fast-food place. If anything, that adds an everywoman appeal that surely only helps Harris - experience of work, paying taxes and earning a crust, at a working-class, bottom-of-the-ladder level. That surely resonates with the electorate.
It says a lot about your character if you consider menial fast-food work beneath you and you ridicule others who do it or have done it This was a big problem in the UK for a long time that has only started to go away.